Once I'd got the gesture and overall proportions in place, I decided to tackle the values by a different method from my usual approach. I decided to key the drawing by finding the darkest dark in the hair, and then move on to the arm and shoulder on the right, rendering it as fully as possible before moving onto the other areas. In effect this was an adaptation of the 'window-method' used in some schools.
The drawing progressed quickly and I was encouraged in my efforts by having got the likeness of the portrait pretty close from an early point.
Since this was a two-week, rather than a four-week, pose I decided to concentrate on the top half of the figure and bring that to as high a finish as possible, instead of attempting to do the entire body and risking not finishing any one area completely.