I made vampy's sig :p

Background doesn't go with the render.
Color splats are not blended well
WAY too much text. Keep the text to a minimum in a sig, as it is just to claim the sig or to suggest the theme.
Color splatters don't blend well
Color scheme seems all over the place.
Her hair seems purple? Did you do that or was that the render? Cause it looks ugly on her IMO.
Render seems a bit too bright IMO.

All in all its a decent first. If you want a ranking out of ten, I'll give you a 6/10. I rated that on a beginners scale, because its not fair to rate this with what I would rate a pro. (If I were rating this based off how I rate the vets, you would have maybe gotten a 2 :p). You will get better, practice makes perfect and look into some tutorials, as they help you learn the program.