My washes aren'ttoo different from what most guys I've seen do. I mix roughly 1 part paint to 3 parts water, that varies widely based on how thick the paint is before mixing and how dark and saturated I want the wash to be. I then add i very small spritz of windex to the mix to make the wash more consistent.
The wash is really important, but I've noticed my toys really start looking good with dry brushing. I consider it more important than the wash. The big thing about dry brushing is to remove as much of the paint as possible from the brush before touching the toy. Wipe that brush off on a rag until you don't think any paint is on it. You're always able to add more dry brushing, but you can't take it away.