As you can see, I practice a lot. Donno what to say. You just draw and draw and draw. Don't focus on particular things, treat your animation like a single piece of art, not bunch of small doodles. Then you'll be noticing mistakes you made and be able to fix them in your next animation.
Gotta say, well done. Your talent surpasses many animators I have seen. You do this professionally? Like, as a job? Or is it just a past-time thing. The way I see it, you could've easily been hired by an animation company, if you haven't already ofc.
Please excuse my somewhat "poetic" English, I just saw the last episode of Game Of Thrones. Man, is it a good show