Right now I'm taking a character design class from Steve Silver (awesome). He told us he got his start by doing caricature and that it's a great way to practice character design. I can totally see why - It's great practice in breaking down someone's face/stature. You can challenge yourself to get as much likeness as you can with the fewest lines. I've actually got an ongoing list of people I'd like to try caricatures of.
Today I did this one. See if you can guess who they are. Hint: They're badass brothers!
Something I'd like to improve on is cleaning up my drawings... My overdrawings always looks like crap! I don't know why.