Proportioning

If you're following these posts, you'll have begun to notice the ladder of horizontal lines going down each piece. I have always eyeballed my drawings - done them directly from pictures, even with the pen. While this is sufficient most of the time, the delicacy of a portrait means that finding a likeness to the subject is a matter of a millimeter or two. So I use the pencil ladders as a measuring technique. And it works.