It's something all of us artists hate to do, but it's a right of passage, and one I'm still working on myself. But you've gotta master hands. Draw fists and hands till you never even want to think of the word again. This is a great piece, but the hands stand out as incorrect, and it hurts the impact of this otherwise great work. Spend an hour a day drawing hands and fists, and know the anatomy inside and out (prolly the first step). Also I recommend that you draw each of your characters from scratch versus using the same template. The continual practice and muscle memory never hurts. Keep up the good work and I wish you success on your journey.