The following colors are the ones I use most commonly to wash with:
Paynes Gray is actually a mix of dark gray and midnight blue so the was is actually a very deep blue. It doesn't turn colors as dirty as a true black would.
Starting with the darkest wash, paint everything that you are going to wash with that color. Prepare the wash by squeezing some paint onto your palate then mix in some water until it has the consistency of milk. Paint the wash solution right over every part that needs to be washed. The wash will naturally fill in all the folds and recesses. When you've finished washing everything, take a break and let the figures dry. If you don't let the wash dry sufficiently, it will bleed into your highlighting.
Be sure to let your basecoat dry too before washing on top of it otherwise your basecoat will run also.
As you get to lighter washes, you will have to take more care so that the wash doesn't run off into previously painted sections. As my target areas get smaller and smaller, I use progressively smaller bushes. For the first wash, I use a number 3 brush a nd for the small areas like the face, I use a 000 to apply the wash. It just takes a little practice.