black shadow on the face seems too dark, nothing else is covered in such a dense shadow, so it's hard to believe the lighting would be so harsh in just that one spot. The lack of fingers is a little weird. You don't have to define every finger, but try to shape the hand in a more natural, finger-having shape. references are helpful and readily found. the shading on the shirt confuses me, you should worry more about defining the volumes of his torso with areas of light and dark. if it's supposed to be his muscles showing through, it's a little extreme (air-tight shirt), and muscles are more naturally defined by the way your light source hits them than they are by lines. pose is a kinda stiff, you ideally want the body language of the character to match the personality, and this dude doesn't seem to be rocking out.