hopefully you're able to make sense of my chicken scratch lines ^^;
Basically what I noticed was the legs and weight distribution. The legs needed to be the same length, although keeping perspective in mind, the leg furthest would seem a lil smaller, but not by much since your picture is side on and doesn't have too much depth. The weight would be mostly on the arm on the ground, and therefore the pic should show this. The angle his torso is on would be too forward for this and would require his other arm to be around his knee almost. However if you move his torso back a lil, he can easily be resting it on his knee ^^ also keep perspective in mind here (I've exaggerated it too much on the lines though so it looks a lil retarded *shot*

But anyways, hope that helps a lil ^^ If all else fails, just try drawing through and getting everything to look right first, then erase the parts you don't want ^^