An overall light wash (in terms of darkness and thinner to paint ratio) is fine if you want to tone down previous layers of paint or a camou pattern. Using a dark wash over the whole figure presents two problems: it darkens everything plus the paint does not accumulate properly in the cloth folds/wrinkles. You are better off using a controlled pin wash on such areas as belts, pockets, buttons, etc. This also means darkening the undersides of folds one at a time - trust me, the extra effort is worth it.
regards,
Jack