Another thing to keep in mind. 1 to make yourself looks stronger, in power etc shot from a lower angle. 2 Dynamic shots - keep the angles fresh, be creative 3 Have some point to your shot. Maybe instead of kicking air (i'm not sure how good you are with photoshop) but maybe kick tree or wall or something and photoshop the exploding particles.
Agreed, the costume is great but the photo itself lacks a certain dynamic. He'd seem much more intimidating if he was kicking towards the camera and not just thin air. The background is also much too busy and detracts from the subject.