Your artwork is not my cup of tea. I can tell you how to improve (since you asked), and make it cleaner (look into using a vector graphics program). If you want to stick to traditional, then my best advise is to learn to draw realistic anatomy before you enhance with a cartoon style, then learn about dynamic movement only after that. It'll only help you're artwork in the future. It took me awhile to learn as much as I have, even went to art college (and got a degree in digital graphics) and took traditional art classes outside of school, and even after that I am still learning.