Try not to place specular highlights everywhere. They attract alot of attention and people will just end up looking at the pearl-like 6-packs.
Consider the focal point. Hellboy's abs are more detailed than his face. Basically areas where you've placed greatest amount of contrast are going to stand out.
If you want to practice good lighting, do alot of film snapshot studies. The lighting in film is very delibrate and will demonstrate to you how lighting is a strong part of composition. On a more simple level it's the shapes formed by values.
Here's what I mean
