Marc, for the paratroopers, use khaki as a base color, then...

...shade with olive drab and highlight with a lighter khaki. For the glider troops, use more olive drab (brownish for the woolen trousers, or greenish for the fatigue trousers), and a similar khaki for their field jackets (that is, if you're doing a scene from earlier than Autumn '44. I'm not familiar with Vallejo paints; but I hope I've been of some help. Dave