In the nations of mortals, there is the ever-present threat of the Daemonic, he who has sold his soul into the slavery of Chaos. The greatest threat of the Daemonic is his undeniable ability to recruit, for the prize which Chaos holds is enough to melt the conscience of any man. Immortality. These individuals are often discovered, vent their anger and flee to the Northern Wastes to contemplate their revenge for hundreds of years, for time has no meaning in the land where the ground weeps and plants bleed. It is here that the greatest threat to the nations of the Old World originate. Chaos Warriors are the most formidable fighters in the world, having honed their skills far beyond that of mortal men, as well as the touch of Chaos making them much stronger and tougher than their untainted counterparts.
For the Chaos Lord, there can be no finer soldiers than those he commands with his iron will and vicious demeanour. However, with this elitism comes a high cost, so the general will have only limited soldiers at his disposal. To begin with, the usual rules for characters do not apply here, a Chaos Champion should always be equipped to take down characters, as you will almost always find more characters in your enemy's army than in your own. Secondly, the characters are excellent fighters, do not be afraid to use them. A Chaos Champion has the stat line(except for wounds and attacks) of an Elven Lord, so if your champion encounters another champion, then you will almost always win the combat, a Hero is better than a Lord, and a Chaos Lord is nigh on immortal, so due to this, every gun, war machine, chariot and cavalry regiment will be aimed at these characters. The characters are few and far between, so your foe, if skillful, will have no difficulty killing them off with massed bowfire, cannons, etc. You must prevent this from happening, as not only are they worth a great deal of victory points, but also this will leave your army with a small number of soldiers with no more than 2 or 3 attacks at best, and none with more than one wound(except for Ogres, but then, they are the exception). In all battles you will be outnumbered, except if facing either another Chaos Warrior Warband, or a Daemon Warband, as the cost of Chaos Warrior Warbands is so high that every model is essential.
When constructing your battle-plan, ensure that you use as much of your army as possible, they are too expensive and capable to waste sitting around waiting for an opportunity. Each regiment should be given a specific task, even if it is only to hold ground, or provide cover for another advancing unit.
The warriors available to the Chaos Lord are exceptional, and each has their own niche in combat. The Chaos Warriors are superb fighters, and more than capable of destroying any foe in hand-to-hand, however, they have only one wound and are quite expensive, so they will need to be protected with either magic items(like the Ruby Chalice), or under cover behind Chaos Marauders, etc. Chaos Knights are the most potent soldiers you will have access to, though this comes at no small fee, once in combat, these troops will easily destroy most of their opponents, and be impervious to any attacks of less than strength 4, which includes most Elven infantry and most humans, as well as some Orcs and all goblins, beware of war machines and magic though, as often these will ignore armour. Always give your Chaos Warriors and Knights a musician and a standard, as these are free, making them absolutely obligatory. Being such formidable warriors, they should also avoid getting 'bogged down' in a combat that is below their skills, such as fighting off 50 Goblins, as although they will eventually kill all of the Goblins, it may take them several turns, and if you are unlucky you may fail to injure any in one turn, and face the prospect of actually losing the combat. The best use for these troops is attacking units accompanying the enemy general, or assaulting the enemy's elite units, as the superior combat and excellent armour afforded to them will almost ensure their victory.
Chaos Marauders should form the numbers in your army. While far poorer fighters than Chaos Warriors and Knights, Marauders are still superior to a human or Elf, and come in at half the price. Possibly the most attractive feature of the Marauders is their 2 attacks and 4 strength, something which most soldiers at 12 points can only dream of having. Always accompany therm with the Champions offered, as this will even the odds, as well as giving the unit a higher leadership to test from. Marauder Horsemen are excellent at harrying flanks, as they have no great weight of armour to hamper their progress, and although they cannot carry lances, the flail serves an identical purpose, adding +2 strength in the first round of combat(regardless of who charged). Marauder Horsemen are technically Fast Cavalry, which allows them to perform an unlimited number of turns with no impedence to their move, change their formation by any number of ranks at no impedence and can even snake effectively. This will allow you to place these vicious troops(they can even carry magic standards of their God) right next to your opponent's War Machines and units of archers, etc.
Chaos Chariots are possibly the best chariots in the game. While they cannot take extra horses to pull them, which would increase their longevity, they are ridden by some of the most powerful soldiers in the game, as well as being a bargain for the price. if you chose to have a warlord riding in a Chariot, put them into a Marauder Chariot, as this is much cheaper than a Chaos Warrior Chariot, however this will leave the chariot with Warhorses, instead of Chaos Steeds, but this can be remedied by replacing the horses with Daemon steeds, which will usually increase the speed of the chariot, as well as gaining much better steeds. A Chariot should never operate individually, as they are far too fragile(only 2 crewmen) to survive effectively. For this reason, I usually arrange my chariots into units of about 3, as this allows them to work together capably, which will ensure that with their scythes(which should always be taken) they will almost ceratinly destroy at least the front rank of the unit.
Chaos Hounds and Ogres provide colour and variation to your Horde. The Chaos Hounds are now much better fighters than under the old rules, being able to make use at least partly of their movement, as well as gain a much higher leadership value. Chaos Hounds advance as slowly as most infantry, but because of their ability to suddenly leap forwards, they should be deployed so that they creep up the flanks under cover, then being able to leap out and attack from up to 12" away. Ogres take much more thought. They are tough and strong, but make very inviting targets and have only average leadership, hich all makes them very good fighters, as long as they chose the right fights. With movement of 6 they can move quickly across the battlefield, and with 3 wounds and 5 toughness a piece, they can ignore most archery. Cannons and other large war machines can still injure them easily, however, so they should be appropriately defended, by using spells, magic items, or whatever.
In general, when using a Chaos Warrior warband, you should always keep a strict battle-plan in mind and follow it to the letter, regardless of what happens to the rest of your army. Chaos Warriors, etc. are quite slow, and so if you have to turn to respond, not only has your assault lost its impetus, but you may also be too late to do anything about it. Remember that your key assault troops are Chaos Warriors and Knights, while you use the other soldiers to either hold-up, or if capable destroy, other units, leaving your expensive(though exemplary) troops to massacre their opponents without fear of being ganged up upon.