I was sketching my friend Tim last night and it hit me so suddenly, the importance of accurate values. It's way more important than color, proportion, detail or any other aspect to representational painting.
This revelation came at the perfect time to me because I was really struggling with a portrait and didn't know what I was going wrong. I think the roadblock I used to have before was to be almost afraid of making the values too dark. This fear is really impeding because most accurate values are towards the darker value range.
So a simple 3 step process for the painting below that I did was:
1. Start with a simple charcoal outline to get the basic proportions
2. Use a large brush and smudges of more opaque paint with accurate values. Don't worry about details at this stage. (squinting helps)
3. Once the basic forms are in place, then you can add minor details and refine it a little bit more, but don't go overboard and lose the planes.