Well as far as tabletop quality goes (if painting an army is what you\'re doing) I like using the \"tank brush\" and going from Catachan Green to Camo Green, then drybrush lightly with Rotting Flesh.
Then for the insides of shoulder pads and on kneepads I paint them with Rotting Flesh, and do some grimy kinds of washes with Snakebite Leather.
I paint the guns Chaos Black, metals with Boltgun, and occasionally use some Brazen Brass (such as on the shoulder pad trim).
Then use all kinds of washes on stuff.
If you\'re not painting tabletop quality, it still works as a good color scheme. Catachan Green, Rotting Flesh, and Chaos Black would be the three main colors I guess.
-Matt