Well, my hands for the most part. Here are some of my hand studies I've managed to do so far.
Once I got a rough handle on drawing the shape of my hand I thought I should probably have a go at seeing how they work:
After looking a bit at the skeletal part of the hand I then moved on to having a go at the muscular side of things:
I'll need to do a few more before I can say I know how it all works but I'm looking forward to it!