you realize the more descriptive you get the more likely they'll be able to help you?
you want an evil centaur right?
then make the horse half's hooves be a dark color, like a darker shade of a real horse, to make it look real, then also make the hair on the actual centaur be the same Dark shade of brown(or whatever color the horse's hair is), and have it appear through the helm, but make it look scary, like, untended too, shiny due to the grease. give him black armor on both his horse half and his human chest, with a golden design, and since he's a warrior, give him a poleaxe or halberd, make the steel look darkened and smeared with the blood of slain warriors, make his expression hard and set, and give his eyes an evil look, and make them uncaring, with a deep blue, that, on a different face, would be quite friendly, but nonetheless serve to scare the livin daylights out of all that pass him.
or somethin like that.
>.> why did I post this?
apparently I'm in a bad mood right now, and am on a weird track... please don't be offended, I'm not sure if I'm tryin to help, but I think i might be. bah.