Quick sketches can be a great way to practice drawing faces, as it forces you to capture a person's essence with just a few quick lines and shapes. I recently found some old sketches (from over 12 years ago) that I did while in college. Most of them are from life, done while I was working at the college music library, when I probably should have been organizing CDs, doing homework, or studying! The first one is of a girl doing some music listening homework. Most of the others are of people in the library, or of people in magazines I was flipping through.