One thing i'm noticing in your sigs is that it seems as if you are adding a lot of emphasis to the background and just adding the render on the side where it doesn't get much lookin' at. The back ground is supposed to bring out the render, and make it look better then it originally did, not hide the render away in a corner forgotten.
Here's what I mean:
See how I made it so that the render is popping out because of the effects around her. Also she's not blending in so much you can't see her, but she's not popping so much as to kill the background and effects.
Just a thought, thought you might want some constructive criticism.