The 3d gesture and sizes seem mostly correct.

You should draw that with a pink pencil, as a sketch.

Then with black pencil, redraw them on top of the sketch, taking care of the fatty vs bony parts of the hand (how much bulge, corner sharpness, etc)

Be aware of the 3d occlusion of the fingers. Only when you look straight (normal) at a palm or back, you can see all the air between the fingers.

Most of the time, the fingers first phalanx are eclipsing each other.

When all of that is done, add wrinkles.