Wow, you amaze me :3 Some great stuff you got there. I notice sometimes in your signature the edge around the render is rough. You could smudge it or feather it down, that way your render is smoother and doesn't look out of the picture. Also use curves to fix the contrast and brightness of the render.
For you lastest sig, just awesome stuff. Though I think the stripe in front of her is too wide, you should make it thinner I reckon. Keep them coming Des!!