Nice concept overall!
there are some anatomy issues all over such as:
the pose looks uncomfortable, like the whole torso is a straight line!
the legs are huge for the upper body.
in the arm the two biceps doesn't match
There might be some other bugs but as for now this is what really catch my eye!
i suggest you start drawing the main lines always and concentrate on them and ignore the details until your aware of the main shape already!
Hope this helps you and keep it up
