Here's my first (and hopefully not only) study:
I picked this image because
it was the simplest of my twentyI thought the contrast gave emphasis to the figure and there's quite a bit of economy in the background elements. The turkeys and the movement of the dress add variety. He's also created a sense of movement by having the shadow follow the line of the wall.
This took around two hours. I think I focused a little too much on merely recreating the image instead of learning from it. (Caught myself leaving whole areas unfinished and working on details...) However, I did notice that he often uses very subtle dark lines on certain edges to bring out the form. The shadows also have much more defined edges than appear on first glance. Picking values is something I often have trouble with, so to be able to get fairly close without the eyedropper was very satisfying!