well the foreshortening on the piece makes it hard to offer much in the way of critique. it's an interesting angle. i think you could push the perspective a little more to give it more depth. do things like make the hand reaching out bigger which makes it seem closer to us. i think if you're struggling with proportions and anatomy you should focus on more basic poses like standing, running, walking, etc. try using figure drawing practice tools that you can find on google with lots of great reference.