Nice anatomical studies! It's great that you're focusing on your weak areas, like hands; keep it up and don't be afraid to make mistakes! About your proportions, I think you have a tendency to make the heads a little small and give them exaggeratedly large legs, so keep an eye on that as you move forward. It might be helpful to do some smaller more gestural studies where you focus on getting the whole figure down with accurate proportions with just a few well thought out strokes. Also I second the suggestion that you try drawing from life, regularly if possible.