You are laying out the shapes first.

It is the best way to position yourself. Drawing skills are very important but they shouldn't dominate the search for an image. That can become illustrative.

What about the color at this point?

I started the work by drawing the highlights on the forehead. The color choice was arbitrary. The development of the composition and form is very conscious at this point. Color develops on an intuitive level. By starting with a warm highlight it was natural to use a cool green in the dark areas. At a later stage, a warm ground will be covered with a color that counteracts it. But the ground color will show through the top layer. It creates a complexity to the color interaction and stimulates the viewer's eye.