Love the Iron Man Head, but Ill give you some tips:
Use gradients on that head, it will be very perfect if it have some reflections or Idk, because he isnt made of paper, he is made of Iron. =D
Suggestions eh... Id say your textures are all right, but they need more depth. Use the dodge\highlight tools. Or at worst use bevel and emboss. And organize your shop a little better. Add a title picture or something.