I came up with this recipe to help show that painting Chaos Space Marines can be fairly quick and easy.
Base Coat Kantor Blue Nothing special here, but I avoided painting the gun and the cloth.
Drybrush. Caledor Sky Drybrush the entire model with a medium, 10mm or 3/8" diameter makeup brush.
Armor Edges Retributor Armour Carefully paint the armor trim gold. No need for a tiny brush, I used an Army Painter Regiment brush. Don't fret over small mistakes, we'll fix those later. I also picked out a few details on the gun.
Main Shade Apply a liberal coat of Drakenhof Nightshade to the entire model.
Let it dry, then paint any bone with Wraithbone
Gun and Buckle: carefully paint any buckles with Ironbreaker and then take a small drybrush and pick out the edges of the gun. You can also apply a highlight to the gold details on the gun with the drybrush at this time.
Second Shade, apply some Skeleton Horde to the bone, leather, belt buckle and grenades.
Place some medium sized light grey ballast in a few spots. This light color helps offset the dark armor.