[Tom Martinez]

Mike, I wouldn't work with color yet. You seem to be on the right track. However, I would enlarge the photo to the size of the drawing. Then, get a piece of acetate and trace the features from the photo. Then, lay the acetate over the drawing to check it for alignment. Then, once the alignment has been checked and corrected. I would concentrate on the values of dark and light. Once this has been corrected to your liking, then, concentrate on color. Good luck.