Chris:
Here are a couple of mixes I've ''stolen' from others. The first is a mate, Brian Wildfong and the second I believe from Einion
Khaki
Burnt Umber + Yellow Ochre + Titanium White for the trousers and Burnt Umber + Mars Yellow + Titanium White for the shirt
Khaki Grey
Titanium White, Cadmium Yellow, Cad Red, Mars Black