Last night I did the Boxes and Books exercise, arranging a number of books, including a large atlas, in a couple of different ways, and trying to capture the shapes and angles.
I was quite happy with the results, and plan to move on to Jugs and Jars today while I still have the wind in my sails....
I guess what I learned from the exercise is to look carefully at the relationships between different objects, and to draw what you actually see rather than what you think you see.