You are good on the way, but your piece lacks confidence. It's all a massive amount of tiny scribbles making up undynamic shapes. You could go Baron Yoshimoto and practice making only lines on pieces of paper until you have improved your coordination, and first then sketching. 
Nah, seriously, you can see a good sense of anatomy behind a resonably good picture, but the massive amount of scribbles remove any dynamics this picture could have. Look up crosshatching pictures and see how it is shaded. Perhaps start out with fruit exercisesor other types of still lifes.
You have great potential. Better use it! =)

Nah, seriously, you can see a good sense of anatomy behind a resonably good picture, but the massive amount of scribbles remove any dynamics this picture could have. Look up crosshatching pictures and see how it is shaded. Perhaps start out with fruit exercisesor other types of still lifes.
You have great potential. Better use it! =)