Your animations are rather shakey, if you're animating, make sure you check if the limbs have a line they go in, he shouldn't go forward in one frame and backward in the one after that, it only makes the animation look shakey. You should have an imaginary line to where the guy should head, ease into it and then keep it going, then ease it out.
Also, move all the limbs every frame, it looks so much better because then it's more dynamic and natural. I know in the beginning it'll be hard to do it, but it works out if you keep doing it, make sure to ease everything then too.
That's about it for now, just keep animating, you'll get better :D!