My first 8 Chars where only the human Oathsworn, to paint em all a little bit simultaneously in my use of colors. U can paint em as slop the same colour used for everyone at the same time, skin, leather, metal and so on, shade the parts at the same time and the highlight them. So u will be 80% ready for ever model in less time. Then u could pick various colours for some contrast, without letting them look like a homogeneous army.