I've done 100 sketches of hand, from pictures online. For me to improve hand drawing and also find out my flaws in order to fix them.
I will appreciate critique, give it please as much (and as constructive maybe :D ) as you could)
Try and get a better under standing of the basic hand forms and how the come off of one another and then work you're way into the anatomy and then you can even go into shading but START working on those basic forms cause some of the hands become out of this world or cartoony
I see a lot of good starts in your gestures! Very impressed with the amount too, you're definitely on the right path to improvement! I agree with CloneEnjinear, there's a bit of a cartoony vibe to your hand gestures that seems to originate from a lack of understanding of the underlying anatomy. You could try to, instead of replicating the hands as you see them, draw their underlying structures the same way you would with full body gestures.
This artist gives a very good demonstration of breaking down hands into basic shapes. If you can focus on getting these basic shapes right, they will be the foundation of finished hands. A good foundation means a good end result! :)
One thing I'm seeing a lot in your gestures is that the fingers appear wobbly and disjointed from the palm of the hand. If you focus on these basic construction shapes first, that is something you will be able to avoid almost immediately.
Quantity is also very important for art (keep drawing lots!) but it wouldn't hurt to take 30 minutes every now and then to REALLY focus on one hand gesture and go all the way in-depth, so you can focus more on the structure and then realize the details on top.