Its a new system, a new art program. Its like drawing with a pencil your whole life & then switching to paint brush, it's a new tool & will take time to get used to. You wont be amazing at first.
I recommend you practice on here, being a perfectionist can make practice tough, as you'll usually judge yourself before you even finish a painting & then just erase it, but try to loosen up a little & learn the tools. Freehand. I started out pretty crappy on here, but I learned by watching others paint, and you can do that by watching people's playbacks & taking mental note of the tools they use & how they use them. As long as I have a playback to watch I can recreate something similiar to the original's art style.
The best thing you can do is be patient with yourself.

Thanks SeaGlass :'D

I agree watching people draw you learn alot! ^-^ But draw in your own art style. :)