I adjusted the underdrawing a little bit after hiding it for a day and using a mirror to help me spot the really wonky bits. It's not an anatomically exact drawing, but it gives me an idea of the proportions and features.
After wiping off the excess charcoal and fixing the remaining shadowy lines to the canvas (with Wella hairspray, the only reason I have the stuff in the house), I put down a layer of Payne's Grey thinned out with Liquin. I prefer Gamblin's Galkyd Painting Medium, but it's not in distribution o'er here. *sigh* In fact, I would use all of the Gamblin products if they were available here .*hint hint, wink wink*
I would normally block in the shadows on the face with the first color layer, but the lighting is still unresolved as I will be painting in three different places (studio, model's home, and convention/fair hall). The background/backdrop is also undetermined as of yet.