Sometimes (and I hope I'm not giving away any industry secrets here) it's easier to just take a photo of your hand drawn image, and work it up in Photoshop. You get nice little surprises when you do that. In this case, I was working on a piece of onion skin paper, so I slipped a piece of randomly marked up copy paper underneath. See that little squiggle coming off his left elbow? The one that looks like a loose wire? That was a total accident, but I left it in because I liked how it looked. You have to be able to recognize these little "mistakes" though. Otherwise it looks like you're trying too hard.