In honor of the sketch crawl I was going to participate in today but decided I didn't want to drive an hour both ways in the snow to get there, you can look at these incredible sketches from Adebanji Alade. Just looking at these makes me want to practice, practice, practice so I could try to become a tiny fraction as good as he is.
He offers many tips for anyone who wants to sketch people you run across in your daily travels...subway, coffee shop, wherever.
Check out this sketch that he turned into a color mixed-media piece. Look at the green on the brim of the hat. Gorgeous!