I think it’s mainly the sleeve and the gun throwing me off. It’s so flat, but I don’t know how to shade it. I drew the sketch and flat watercolours traditionally and painted over it digitally to achieve a cool effect but it looks horrible. Please help

I think it’s mainly the sleeve and the gun throwing me off. It’s so flat, but I don’t know how to shade it. I drew the sketch and flat watercolours traditionally and painted over it digitally to achieve a cool effect but it looks horrible. Please help | Artwod Feedback