Brief update: I've been sketching hands a good bit and finally did some digitally that I'm pretty happy with at the moment. Granted, I had rendering and Ctrl + Z on my side in this scenario, but I still don't think I'd be able to do these when I posted originally. I'd love some critiques on how to further improve. (I'm not as happy with the top right one - I used the airbrush too much when more confident shadows would have created better dimensionality.)