I think the biggest issue is with his upper body. His rib cage is cut off and is flat (see red markings) that is why his arm looks so disproportional compared to the body. Try to use construction methods for a body (e.g. can be found on Artwod roadmaps) before drawing a character. Lack in volume for the upper body also carries over to the clothes. The lines for clothing should be like contour lines for the shape of the body (see chest area). Since we look slightly from above him we should be able to see the plane of his shoulders. It is also where fabric tends to gather so I added some for volume (see pink markings). Rule of the thumb: hand should be about the same length as the face. I hope this helps. He seems to be a charming character. Good luck! | Artwod Feedback