Mmm, pretty good for a first. The only crits I have is that the text is slightly aliased, you should have made it a bit smaller. It also looks like you blended certain parts of the hair, but not others. And lastly, I don't think blue was the best color to go with. It doesn't really match the background. You should have gone with red, it would have looked much cooler.
But, overall, it's a damn good sig for a first.