Heyy! So first off, getting used to a tablet takes a long time. I got my first tablet 5 years ago (and granted, I was quite young) but it took me 6 months- a year to fully get used to using it. The more you use it the easier it will get, so time and practice are really the only solutions to that.
My advice would be to just work at things bit by bit. Find an art piece you really like and try to copy just the eyes, or ears, or head, for example. After you can get those down, try them at different angles. As a general rule of thumb for when I do this (like when i get artblock or whatever) is I never post these drawings, since you're technically copying someone elses art. For your own personal study this is fine, but just keep it in mind.
Just start small! Start with sketches, and once you get comfortable with that, move up to lineart. Don't be afraid to take a long time drawing even a small object. I'd say "study anatomy and life drawing" but I didn't do that sooo< I still feel I should recommend studying life and all that, because it is good advice I'd probably be way further ahead if I did, but I know it takes a lot of time and it's not all that fun. Also, I wouldn't worry to much about finding your own artstyle when you're just starting out, that sort of thing also happens naturally with time.
Like I said, all this stuff takes time. It's not gonna happen overnight, but that doesn't mean it's impossible to improve quickly. Check out tutorials, especially ones using the program that you use, and try different stuff out. I'm not sure which programs you're using, but if you're using paint tool sai I can help you out with it a ton! I also have some excellent brushes that I use on the daily.
If you want some specific help on stuff you've drawn I'm always open! Just send me over a pm. I hope this helps a little ;;
edit: to answer the hand-drawing/cirlces rectangles question: hand draw! there's nothing wrong with using the circle tool to make a base for heads and what-not, but handdrawing helps you practice much more and gets you used to your tablet!