I would probably work a little more on your figure drawing, especially action posses. you can be a fantastic artist but in the comic book world it's essential to know how to pose your subjects in such ways as they don't seem so lifeless and still. Foreshortening is a huge factor in it as well.
If you haven't already, I would pick up How To Draw Comics The Marvel Way by Stan Lee and John Buscema. It's a fantastic book that all aspiring comic book artists should own. Hell I don't draw comics and I own it, it's still a very useful source.