This section tells you my thoughts and other people's thoughts on the proper uses of your crazed death-machines in power armour. It also gives some comments on which sociopath maniacs with bolters to take to battle.
Chaos is a supremely adaptable force, so you need to determine your playing style first of all. Take a good introspective look and decide if you are a defensive player who like to sit back and shoot the gits or an offensive player who like to chop them into little bits and pieces covered with gore in an orgy of splintering bone and blood!
You then need to choose a chapter that fits your style of play. If you are a defensive player, you should choose the Iron Warriors with their cunning fortifications and weapons batteries, or perhaps tough Death Guard plague marines. If you are more offensive, you should take the Worldeaters, frenzied berserkers that they are, or maybe the cool-headed warrors of the Alpha Legion should be your pick. Of course, if you're a middle of the road person, you should take the Night Lords or Black Legion, both chapters that attack and defend equally well. This gives your army a focus and keeps to the background.
Now we come to the troops. First, the Chaos Space Marines. These are adaptable, jack-of-all-trades troops. It all depends on how you equip them. You can give them chainswords and bolt pistols for close combat, bolters, or form them into those justly feared squads of three men armed with heavy weapons. They should form the numbers, the more specialized elements of your force should be used in key positions.
Almost everyone has something to say about Veterans. First of all, those all Veteran armies that I have seen are wrong and cheese enough to make Kraft envious. Don't even think about taking one. Having said that, one or two squads of these elite troopers can provide a much needed edge. Equip them with heavy weapons to blast the foe while in concealed positions, or assault weapons to have them suddenly rush from hiding in search of skulls for Khorne. They tie up things like Lictors very well.
Chaos Terminators have become the envy of many loyalist Brother-Captains, again due to their supreme adaptability. They can be outfitted for defense or attack, but due to their lack of numbers, should probably be used to bolster a flank or form a spearhead for an assault. The Reaper Autocannon and heavy flamer are the heavy weapons the Terminators can choose from. The former should be used for defense, the latter for attack.
Berserkers. Well if you can't figure out how to use these guys, what are you doing playing a complicated intellectual game like Warhammer 40,000 in the first place? Hand to hand. Period.
Noise Marines and their deadly sustained fire weapons would be good for holding a flank so that their weapons could sweep a massive area of the battlefield clean. They are good against mass nasties like Tyranids and Orks, and can splat tanks very well, so they would be a great choice if you are going to fight the Imperial Guard. Some people say, "Why not teleport Abaddon down near your opponent's psykers with a Noise Marine Terminator bodyguard?" Well, I can't stop you, but I just don't see The Despoiler doing that.
Plague Marines are the ultimate tactical troops of milennium forty-one. Unfortunatly, they can't become assault troops (plague knives suck), and they lack the capability to take out tanks and hive tyrants. This makes an all-Nurgle force very risky. Blight grenades are great for stopping Orks and Guardsmen in their tracks, but don't expect them to do much against smaller, elite forces.
Thousand Sons Marines. Why would anyone take these guys? They are immune to psychology, which is almost worthless because Space Marines rarely run away anyway, and you lose D6 of them every time energy drain is played! If you want to do an all-Tzeentch force I applaud you for sticking to the background, but would strongly suggest you save the five points apiece.
Greater Daemons:
Lesser Daemons:
If you think that this is just a bunch of junk, just about every Chaos Page on the net has some tactical advice for the budding Chaos Champion. I suggest that you go elsewhere for more tactical knowledge. I will post some of the best tactical tips I come across here when I get the time.