The first step? Mixing the black paint. I use french ultramarine blue and burnt umber, this makes a wonderfully rich black color, and when mixed with white, you get the nicest shades of gray you have ever seen. I always mix my own black paint... I find it gives me more control over the warmth or coolness I am trying to achieve. Second step? a light wash using just a thin wash of your black paint, no white paint at this time... mix with a medium of your liking, I use turp, linseed oil and damar varnish. Notice we are also working from a black and white photo copy of the painting, another tool to help us not get distracted by color while we try to make a convincing interpretation of form and space.