So my mental game for quite some time with hands is "Look at them and study them, then draw without looking at them at all". Tricky as hell at first because hands almost seem to transform or mold to help you express and compliment both your external and internal emotions. Once looking at them though for a certain amount of time and thinking of them as simple or basic shapes, you start to realize the how and why's of the hands.
Studying the under structure of the hands will help make things even that much simpler. So I would say pick up an anatomy book to delve a little deeper into why things are the way they are.
So the test is>
first: spend 5 to 10 min analyzing
second: Draw what you saw!
If yah want more of this stuff from me and anatomy ref hit me up through meh note. Thanks