Highlighting and shadowing each colour individually is the best method overall but in small scales it can really be almost impossible to do, luckily 1/35 scale is just small enough that you can use a single highlight colour and a single shadow colour and get pretty decent results with most camo patterns, if you pick the two paints carefully.
Stefan Müller-Herdemertens's method, which is of this type, is explained with some pictures in Tony Greenland's armour book, using a light 'warm' grey for highlighting and a sepia for the shadows. I don't remember which two paints exactly (they might be in a prior thread if you want to try a search) but the exact ones aren't important since one can mix something yourself and use that, and you may not be using oil paints anyway.
Try a light mix of white, yellow earth and dark brown for the highlighting colour, black + brown or black + green for the shadow colour and work slowly and carefully with a fine brush, see how you do.
Einion