Weird hands

I started out with a photo ref. It came out bad because I was just eyeing the photo with out thinking of proportion. The length of the thumb in relation to the palm is really important. After a few more studies I saw that the thumb can pass the palm around the knuckle area (if extruding). My second drawing (first row, second hand), was of my own hand but the fingers came out messy unnatural. I tried the pose again and got it a little bit better. I keep messing up the position fingers can do and can't do. In the last row I decided to try weird positions to learn the extent of finger flexivility.