One of the mental techniques about hands is to think of them as a whole other body. Hands are expressive. They have their own gestures and can be used to express very strong sentiments: praying hands by Durer, punching hands in a comic book, or flowing hands in a hula dance.
I am going to go back to the drawings with a fresh mind and some warm up sketches and draw what I know about the structures of the hand.
Filling a sketchbook with just hands is a great way to understand the many forms they take.