First step is to force yourself to draw the bits you're not good at. Don't hide the hands behind the backs, get good at drawing them by bashing your head on them until it sticks.
As for corrections, you're mostly alright save for the arms looking a bit short. elbows usually go down to about the lovehandle area just above the hips, while yours are barely clearing the ribcage.
Study up (read: draw in as much detail) some skeletons and later on muscle groupings, then go back to cartoony stuff. You have to learn the rules before you can break them safely.