I like to use Gimp really, I'm still learning it though. I don't know how to draw without drawing over the lines really, which upsets me a lot. But I've been learning, and even messing around with filters did quite a few good art pieces. Gimp's free, and once you mess around and get used to it you can practice and make good art for free. That's what I like about it. But, I'm still learning how to use it.
I'm really confused on it but I might search YT on how to draw better on it.