I like the cross-hatching rendering you've got; they add a lot to the piece. I don't know what your drawing process is, but my advice would be to really nail the movement and shapes of the piece in a lighter sketch before you start adding details, like hair and the lines on the hands and feet (maybe you already do this and just erase the guidelines, I can't tell). I notice that your longer lines are made up of shorter lines, which makes the overall shape more visually complicated. If chicken scratches are your style, don't let me tell you off. I'm only mentioning them because they can sometimes make weaker shapes.
The "line of action" is very difficult to incorporate. In some ways, I think boiling it down to a single line makes dynamic poses harder to master. I recommend taking advantage of curved and straight lines to show motions as well. It helps me more to capture the motion through deliberate shapes and lines. I draw the pose as a whole, as well, rather than part by part, before breaking it down into smaller shapes. I think the advice of keeping it simple for as long as possible has helped me significantly.
As for having extra time otherwise, your details are very good. You seem to have a good understanding of the lighting in the piece.
Hope this helps.
