One thing I learned was that my brush pens turn into ink faucets in the Las Vegas heat. So I was only able to get a few of those drawings in before I had to switch to another pen. Darn.
I'm taking a watercolor class, and my instructor suggested keeping a sketchbook of brush pen/silhouette art. I've been using a brush pen for a little while already, but drawing in silhouette was not something I tried to do very much. It's been very refreshing to look at subjects this way.