Legato from Trigun

I drew this last year, and been trying to work on fixing it up on and off. I can see what's wrong with it and I can't figure out how to fix it. ^ ^; Anybody see anything please let me know how you think I can fix it? It would be much appreciated! ^ ^

P.S. i can't figure out how to fix the arm cause I know it looks way off, at least in my opinion. ^ ^;