Fate, I love you.
BTW, that's my German soldier in the bottom right hand corner, but is way outdated now. Are you interested in the entire character set? I must say, it doesn't look half bad.
Showkaizer gave me some hints as well, and the best one he has given me is to try to keep the contrast. As you can see from my example there, there is not enough difference in color.
I can give you a hand, if you'd like. I'm planning on making a game with all these elements within it. Are you planning on making a game with these characters, or just spriting?
Glad to see someone else in this wide world is interested in spriting soldiers from WW2. I thought I'd never see this day...