I took a workshop yesterday with Clayton Beck, a very good painter who is a protege of Richard Schmid. We worked on values- using a middle value as the lightest light in one sketch, the darkest dark on another. In the afternoon we did a long pose with our model and I chose to work with dark values. It's really hard not to reach for that white to make bright highlights! It was a great exercise in controlling values and I intend to try it some more.