The shading on the helmet is nice but the rest of the body could use a major adjustment. One thing you could do instead of adding lines of texture across the body to give it detail would be to actually make it look like detail. Say if you have a shirt that is "loose" so it has waves on it in places then make the actual "wave" darker then the area around it lighter. It helps when you make a skin to use realism- look at someones shirt/pants whatever one day while they are wearing it and see where the clothing waves, folds etc...
I usually do that with my skins.