Hi James, I think these are great and really expressive, which is cool. If you want to go for more realism I would say the main thing would be to learn the anatomy of the hand. You could then support this great form work with underlying bone and muscle structure. You don't need to know every ligament, just the landmarks and what we can see on the surface ('Atlas of Human Anatomy' by Stephen Rogers Peck is a good book). Structural understanding would not only help with some of your fingers that are perhaps flexing a little further than is possible, but also would help you to draw what you "know" as opposed to just drawing what you "see" Hope that's helpful. It's certainly helping me with my scribblings 😊