Hey Wendy, Your hand drawings are very nice, they have a good solid feel. One of the things I noticed is that your wrinkles are very flat, which flattens out the forms. Try to make sure the wrinkles work for you as cross contours, that way they give a more 3 dimensional feel to the forms. I did a couple of sketches to show you what I mean, I hope it helps :)

The form on the knuckles on the left side is great! It starts feeling a little flatter on the left, which isn’t the end of the world since that doesn’t seem to be the focal point. However I think it’d work better if you had the leftmost edge of the pinky be a tiny bit lighter than the rest of it instead of darker, to show bounce light. I also think it’d look better if the angle change between the hand and the forearm was less extreme. When I try to put my wrist in that position it’s pretty uncomfortable. your anatomy and shapes look great please let me know if you have questions!