I participated in the 2012 Sketchbook Project at: http://www.sketchbookproject.com/
My approach to the sketchbook was to use images from old show cards cut apart, drawn on top of and into etc... Here are 5 images from that sketchbook that now lives at the Brooklyn Library as part of the Sketchbook Project. I can't recommend this project enough and encourage everyone to take part. It is a great opportunity to do drawings that you don't normally do.