I'm going to focus on the first one. I feel it's the better of the two.
The arms are slightly too long (the wrists should be level with the crotch). The hand on the left is slightly larger than the other. You've drawn them well enough, except that the middle fingers should be longer than the index fingers. The lines indicating the knees should be moved slightly up the leg. The collar bone's a little low. Try not to be so pointy/angular on connecting places like the neck or waist. The eyes are just slightly too far apart (eyes are one eye length away from eachother). Remember that hair naturally masses together, so you don't need all those long lines separating it all in the back, just the bangs. Lastly, concerning the feet, they're very block like. Remember that feet are more narrower towards the ankle, then fan out.
If you really want to improve on hands and feet, just google a bunch and fill up a few sheets of your drawing of them.
Also, you haven't failed in the least. Art takes a LOT of practice. Don't give up!
Thanks ! This is exactly what I was looking for !