Any Dwarf general, the King, Dwarf Lord, Steward of the Stronghold, or mighty hero should know the basic principles of the tactic and strategy. Below, you may find collection of advice's and tips for all Dwarf leaders.
The first, and probably most important thing for a dwarf general is to forget all he ever saw or read about the tactics of elgi or umgi, or any other race. Those tactics won't work for Dwarfs! We, the descendants of Grungni, and Grimir do not have chivalry, fast moving shock troops, or expendable missile screen units . All we have is solid rank and file troops, and heavy artillery support. Forget then about swift runs on the flank, hit and run techniques, outflanking maneuvers, or other nonsense. But, let's start from the beginning, namely army selection.
It's extremely important what troops you will choose, and how many of them will you take to battle. The choice of troops, I leave for you. As a general you should have own unique style of play and favorite units you like to use. The very important thing, is the size of your units. Dwarfs need strong regiments, 4 or 5 ranks deep to assimilate all the missile fire (since their mobility is low) and combat wounds opponent can score and still be able to do some damage. Units to small will probably be severely weekend by even small causalities. There is no point in denying that, our people rarely have occasion to charge (and therefore strike first), or get away from the line of missile fire. We usually are able to wait it out, and strike back, and to do that, our units need to be big. On the other hand, the bigger the regiment is, the less mobile it gets. In addition, by deploying a very numerous unit, you spend a lot of money, that might be used elsewhere. For example, 40 Iron Breakers cost 800p, but it's not likely for them to destroy 8 VP worth of enemy units. Therefore, you can clearly see that the half of the unit will never be used. In other words, you deploy one big unit, where you could deploy two or three. And as you probably know, two units cooperating with each other, are in most cases more flexible than big one by itself. Large regiments tend to be picked out by the missile fire from the beginning of the game, and are easily outflanked, outnumbered and crushed by enemy force if left without flank guarding units. Other good advice is to always take some artillery support. Your troops, no matter how good they are, will never perform good if they're not supported by heavy bombardment. Finally when choosing your characters try not to get overboard with the runic items. It's easy  to spend more than 800 points on a single rune smith, and around 600 points for a dwarf lord. That's in itself more than a thousand points, which is equivalent of a small army. Remember that quality is not always batter than quantity.
The golden rule when planing your strategy can be contained in for short words: "minimize your weaknesses, maximize your strengths". But what are those weaknesses, and strengths? First I'll go over the weaknesses of the Dwarf race. Let's face it, Dwarf's are not perfect, and most of generals realize that their troops have certain limitations, and weak points. The main flaw of our troops is of course mobility. As a leader you should never try to outrun your opponent. This will never work. Dwarf mobility can be slightly improved by using such items like Golden Scepter of Norgrim, Rune of Passage or Fiery Ring of Thori and Rune of Slowness ( those prevent enemy from moving rather than make you faster). Learning to use those useful items can be very beneficial, but won't win you a battle. What then will? The key to success on the battlefield is to be at the right place at the right time. How to do that, having the slowest troops in the world? The simple trick is to predict what your opponent is trying to do, and plan your moves in advance. Having a good battle plan, or even a general idea of what you want to do is half of the victory. The rest is just pure luck when rolling your dices...
Another weakness is the low initiative of our troops. This means that almost always they will strike last, unless of course they'll charge. Sadly with so low movement value they will not have this opportunity so often. There's virtually nothing that can be done to improve the Dwarf initiative, so you just have to learn to live with it. If you know that your troops will strike last, why then don't give them double handed weapons? This will not impair their combat ability, it can only improve it. If you know that your troops will probably not have an opportunity to charge, give them spears or extra armor to improve their combat ability and survival rate. When you expect your opponent to be offensive, try to get all the bonuses you can on your side. Try to grain higher ground bonus if possible, use obstacles and terrain to aid you. Having a command group (champion / hero, standard bearer and musician) or at least a standard bearer in each unit is also important, as it gives you combat bonuses.
The most painful for a Dwarf army is the lack of Wizards and their powerful magic. This theoretically is recompensed by the wonderful runic magic, but every general knows that runic items are very rare and expensive. Often more expensive than a service of a hireling wizard. Since Dwarf people don't practice magic, and have n Wizards of their own a good leader always should try to minimize the enemy magic capabilities. Dwarfs have some resistance against magic, that allows them to use dispels without the presence of a wizard or other magic user on the battlefield. Sadly this special rule is not enough to stop the enemy spells. The ages old tradition is to always have the sacred battle standard inscribed with the holly rune of Valya as the army battle banner. This gives your central units good anti magical protection. The spell breaking runes are also very effective in the hands of a skilled rune smith. You should concentrate on the capabilities of your own army. Hireling allied Wizards is rather bad idea and rarely does your army any good. It's far more effective to field the dreaded Anvil of Doom to enforce the magical capabilities of your troops. The lightnings from the anvil maybe aren't the strongest spells in the game, but are effective enough to hurt almost anything they'll hit.
A battle is won by good tactic and planning, not by magic, so you should not worry to much about lack of wizard characters in your army. They're not as important as it may seem.
Dwarfs are not the best missile troops in the old world, but their ballistic skill is not so terrible as you may think. Dwarf crosbowmen and thunderers are not the best shooters, but they can aim good enough for our purposes. Those units are not designed to shoot out the enemy units, but to give you cover fire when you advance and soften op the enemy units before combat. The main firing force for dwarfs is the artillery, which in most cases don't use your troops' ballistic skill for aiming.
Dwarfs don't use chivalry. That may be considered a weakness, but I thing about it as an advantage. Other races spend enormous amount of points to field those small (usually five man strong) chivalry units that die so easily when hit by a cannonball, or a flame, while you can buy some good war machines or one or more solid infantry units for the same price.
That would be all weaknesses of the Dwarf people that I'm aware of, so let's move on to strengths of our race.
Dwarf courage is almost legendary. Our high leadership value makes us almost immune to panic or fear caused by monsters or undead. It also makes us hard to beat in close combat. This is an important advantage that makes dwarfs good defensive troops. The great leadership can be reinforced by at least partial command groups (standard bearer and eventually a musician) in each unit, the presence of a general and a battle banner and the influence of some magical items and produce fearless and almost unbreakable force. In most cases opponent will have to kill at least 7 or 8 warriors in one turn to have a significant impact on your brake test while he needs at least 10 to be almost certain to brake you ( in this case I assume that your unit is at least four ranks deep and has a command group lead by a hero or a general and includes a battle banner).
Dwarf warriors also have a superior weapon skill and are very though. This means that most of the enemy soldiers will hit them on 4+ (or worse), and wound them on 5+. They in turn will hit most most of the opponents on 3+. This makes Dwarfs fearsome close combat troops.
Remember when few paragraphs above I was talking about Dwarfs rarely having a chance to strike first? Since they are good  and very though fighters this flaw does not seem so terrible  now. Use those three properties of Dwarf fighters when creating your units. If you keep in mind that you never strike first, bur have weapon skill, toughens and leadership advantage over most races you should be fine.
Dwarfs have good, but expensive characters. This means that you need to use your points wisely and distribute them evenly among characters and their magic items. As I said before don't get overboard with runic magic. Three items, full of runes for your lord can use up most of your character point allowance. The same goes for rune smiths which alone can take up to 900 points. Rather than giving them the maximum of allowed items try to think what function each of your characters have on the battlefield, what tasks you want him to perform and choose his items according to his function. For example if your hero is a part of a command group of one of your units, it's best to give him some item that influences the whole unit. If however he is your Lord's bodyguard (and his task is to accept any unwanted challenges) you may give him some good armor, and a magical weapon to stand a chance in the duels with enemy heroes. Ana logically if you use your rune smith as a spell breaker put him in the unit with your general so he does not have to answer any challenges. Rune smiths are awesome warriors so he should have no problems fighting with rank and file troops. This way you save points on expensive magic weapons (but you waste two magic item slots but that's another story). In general, characters can be divided in two categories: leaders and mighty heroes. Leaders are those champions and heroes you include in the command groups of your units. Their main task is to allow units to use their high Ld and improve unit combat abilities. Mighty Heroes are characters that fight in all the challenges, deal enormous damage to opponent units with their multiple attacks or tie up the most powerful opponents to prevent them from hacking through your rank and file. Both categories are equally important, and you need to learn how to distribute points between them. When you'll choose your characters think about where to place them. Put your leaders in command groups, and your mighty heroes in your main combat units. Don't put all of your mighty fighters in one unit. This would indeed make the unit really powerful, but such group of powerful characters will attract lot's of missile fire. In addition it's far to easy to outmaneuver such unit to make it effective on the battlefield. Put your best fighters in two or three strong units (if you want to give one unit more power put your general or rune smith there along with some hero - bodyguard). Also think where your Battle Standard Bearer will have greatest effect, at the same time being relatively safe from any harm. When assigning your leaders to your units bear in mind that they're most effective at front line units. Your light support, namely crosbowmen and thunderers, who usually occupy some hill behind your warriors may not need to include champions or command groups (unless you expect to encounter some special deployment troops). On the other hand a front line unit of crossbowmen armed with double handed weapons really could use a command group. Dwarf Special Characters are better than special characters of other races because you can switch and swap their magic items any way you wish. You may field them magically unarmed to save points, and yet still benefit from their special rules, or you can equip them with a beardy combination of your design. When choosing your character remember three things: Distribute points between your Mighty Heroes and Leaders, don't go overboard with magic items and put your characters where they'll be most effective. Whatever you do, bear in mind that being beardy does not always mean being victorious.
Now let's go over the choice of troops in your army. The Dwarf army can be divided into sections: Command, Compulsory Units, Elite Units, Light Support Heavy Support and Tactical Support. Each group has different task on the battlefield, but all must cooperate with each other in order to achieve victory. If a Dwarf army lacks one of those parts   it's efficiency is greatly impaired.
Command models are the Characters and Command Groups. I wrote about characters and command groups in previous paragraph, so I will not repeat myself.
Compulsory units are the backbone of your army.  Those are the units that do the most fighting and take the most damage. Their main task is to tie up the enemy units and make them busy. They don't need to deal a lot of damage, but must be strong enough to hold their own against large enemy units and crush the smaller and weaker ones. Compulsory units don't usually include any Mighty Heroes because they're needed elsewhere. They however need at least partial command groups to improve their combat ability. There's no rule telling which units from the army list are compulsory. It can be clansmen, miners or even elite warriors like iron breakers or hammers.
Do not confuse Elite Units with elitary troops like longbeard or hammerers. Elite units are units designed to attack, crush and destroy any enemy unit they are able to get in combat with. All your Mighty Heroes should be placed in elite units to give them extra destructive power. All elites need full command groups (ok, if you really don't want to field musician then don't but he sometimes come in handy), and all the support in form of magical banners and magic items they can get. As with compulsory troops there's no rule that indicates what troops you should use burt elite troops are probably best suited for this work. It's best to have at least two Elite units in your army, since one would be to vounerable.
Light Support units are your missile troops. Their task is to pick out dangerous enemy units which are out of combat and pound them with missile fire. Light support should be placed behind your compulsory and elite units, on elevations or on flanks. When shooting try to concentrate all available firepower on one target. If you split your fire between several targets you won't be able to make enough damage to either of them. Light Support units would be your thunderers and crosbowmen.
Heavy Support's role is to damage enemy while he is far away, and soften up his hard hitting units before any combat occurs. Your Heavy Support or if you prefer artillery is most effective when positioned safely behind the front lines on hills and other elevations. The special case is the flame cannon which need to be placed way up in your deployment zone because of it's short range and the risk of accidental shoot. Bolt throwers seem to be the lest effective war machines available, so my advice is to not use them. Organ Guns and Cannons are excellent at damaging large multiple rank units, but slightly less effective against chivalry (since those units usually have only one or two ranks so the bouncing of the ball have little or no effect), unless they can shoot at it's flank. Stone throwers are effective against large groups of enemy units, where they still have chance to hit something even if they'll scatter. Flame cannon is good against anything that gets in the range, save maybe skirmishers who's formation makes them hard to hit with the template. To use artillery effectively, you need to learn to guess ranges accurately. Always use the same ruler or measuring device so you get familiar wit it. Also try to make up some reference distances: for example if you spread your fingers the distance between your index finger and thumb is approximately 6", while the distance between your elbow and the bottom of your hand is about 12 inches. Those tips should help you to learn to recognize the distance you need to guess rather quickly. It's also good idea to fire with your light support units first to get the general idea about the range (some players however insist on firing artillery first, and missile units later to prevent such form of cheating). One more thing about targeting. Try to concentrate your fire on one target (if possible).
Finally there are the few units I classified as the Tactical support. Tactical Support units perform special tasks on the battlefield. The example of tactical support units from other armies are for example flyer and special deployment units who get behind the enemy lines to take out the dangerous war engines. However units that are very specialized to perform certain tasks also can be included in the Tactical Support category. The category itself is quite special, because it's presence on the battlefield isn't necessary. You can win without ever using your Tactical Support, yet if you decide to field some of them, they may prove very effective.
The most obvious Tactical Support choice is of course the Gyrocopter. It's can perform various tasks, from which I'll describe three most important ones. First one is to use it as a support for your advancing compulsory and elite units. The steam cannon effect or swift bombing runs can disorganize opponent or even stop him for advancing (this happens when your opponent tries to hunt down your gyrocopter). Later, during the close combat Gyrocopter may use it's steam cannon to shoot at the rear ranks of fighting units (since this is a template weapon, if you place it carefully enough it will not hit your troops). This proves to be very effective tactic. If you're not afraid of risk you may want to send a squadron (two or more) of invisible (rune of disguise) gyrocopters behind enemy lines to pick out the enemy war machine crews with their steam cannons. Finally an invisible gyrocopter may hover over the enemy units to prevent them from marching, and therefore give you one or two more turns of heavy artillery fire.
Another Tactical Support unit would be large crossbowmen unit equipped with double handed weapons. It should be deployed way up in your deployment zone in a wide formation. This gives it an extra few inches of range, and a good firing position. As the enemy advances you should regroup your unit into 3 or more rank formation and use as compulsory unit. You also can move it along with your front line troops, to get to a good firing position and then expand your formation. As you can see such unit has a dual role - it's Light Support and Compulsory Unit at the same time. That's why I placed it among the Tactical support units.
The last of Dwarf Tactical Support units are Slayers. With unlimited number of champions in the unit, all the slayer special rules and different weaponry they are very dangerous opponents. Their primary targets are big and powerful units, monsters or characters which they can destroy. Even though each of them can carry different weapon it's best to give all them additional hand weapons to increase the number of attacks they can make. If you plan to use them as an Elite (i.e. to attack and grind down powerful units) it's best to put it behind some well armored compulsory unit for protection from missile fire and fill with some powerful champions. There's however a different and more interesting use of slayers. Since almost everyone knows how dangerous they are, and they attract lot's of attention due to their colorful nature, they are great for distracting opponents. While he amuses himself by shooting down your unarmored slayers your compulsory and elite units can advance relatively safely. Finally you can use small groups of Troll Slayers as a rear guard for your altillery since they are good at killing any large flying creatures.
Now you know how to prepare for battle, so now let's talk about the battle itself. Since there's no single tactic that would work against every army I'll just talk about some basic principles like deployment and how to get your troops into combat.
The most widely used Dwarf tactic is the Line. You simply spread your compulsory and tactical units along your deployment zone in such way that when enemy initial charge comes some units may swing around and charge the enemy from the flank, while the units from flanks advance to intercept any slower moving troop attack. This tactic is probably the simplest one,  proves to be effective  only at rare occasions occasions because the wide formation leaves the flank units vounerable.
Dwarfs are strongest wen they're concentrated in small area where most of your compulsory and elite units can benefit from presence of General and Battle Standard. They can also help each other by charging the flank of an enemy unit in close combat with an unit close by. Also your Light and Heavy Support units benefit from such deployment, because they are well protected. Such grouping of your units is often called Bastion or Castle formation and is very effective for defense. If you can get some obstacles to defend and higher ground bonus, along with some cover here and there your army will be very hard to defeat.
The interesting aspect of the castle formation is the Refused Flank. You place all your units on one flank, leaving only some Tactical support on the other. This tactic also known as Corner Hugging is very effective defensive strategy, because it gives you a lot of opportunities to fire. This tactic also prevents enemy from making flank attacks or attempts to surround you. That's because because your front as well as your flank are better protected than in standard castle formation. Both Castle and Refused Flank have two downsides. Your units are vounerable to alltillery with large area of effect like stone throwers. In addition since you build your defense line near the table edge, any of your unit that will flee (voluntarily or due to psychology or casualties) will probably be lost.
Sometime however you need to be offensive, and that can be problematic for army with such low mobility. Generally dwarfs are better of defending than attacking. If you want to advance you may employ a method called Steamroller tactic. You simply place your compulsory and elite units in a single file with a big and strong compulsory regiment at front. This unit will take all the missile fire while you advance, and then fall back when you're in good attack position. When you are far enough branch out from your formation and wait for initial charge. If your opponent is foolish enough to let you charge it's even better. The Steamroller works wonders if it's combined with some diversion made by Tactical Support and "dummy" compulsory units.
The alternative tactic is the Slow Advance in which instead one block of strike units you use two which advance at the same time. This forces enemy to split fire between two groups and therefore minimizes the damage he can deal in a turn. Tactical Support is essential since without it your units will be quickly outmaneuvered and shot down. Use crossbowmen for cover fire, and gyrocopters for distraction. Place large slayer unit  between the two strike groups. The temptation to shoot down some slayers may be great enough to make your opponent forget about the main threat- your strike groups. Remember about Heavy Support cover fire while you advance.
That's basically all what I can tell you about basic tactical principles. Since each army is different, have different style of play and use different tactics you need to design different strategy for each army, and each player. And what's most important your strategies must fit your individual style of play. If you for some reason don't like some tactic or unit simply don't use it.