I found it helpful as a practice to employ the use of a light board and trace free hand various forms of imagery (primarily from photography) to develop the proper "feel" .
It's always quite a surprise when you think you need to do one thing to get the desired result, yet discovering the tracing practice proved otherwise, forcing you to adjust to the correct way the drawing instrument needs to move.
It's a real eye-opener on how your brain says to go this way on so many things, when reality says to go that way instead.
Hands, most definitely, are the toughest, I think, though eyes can be tricky to do properly. To do realistically. You can get away with faking, to some degree the hands, hair and feet, but the eyes not so much. I always thought hair and feet were easy.