After a few test paints I finally decided which will be the color scheme for my empire army: Black and Gold. OK, the latter is more a yellowish brown. But that's not what one of these soldiers would tell you if you would ask them, you know? ;)
I used some of my new Warpaints from The Army Painter for these models (all three inks, yellow and the metallics, the rest was done with Game Color and Model Color) and am pleased with the result. I especially like the inks as they are a good replacement for the out of production washes from Games Workshop.