You're throwing crappy text onto a distorted, low quality picture.
It's not a sig, it's a disgrace. No offense.
http://www.gimptalk.com/forum/forum/GIMP-Tutorials-and-Tips-8-1.html
Check out some of those if you haven't already, or maybe Digi will help you out a little. He's the resident Gimp gaffer. (In more ways than one, Ooooooh.)
And there's a nice thread called "Sig advice" stickied to the top of the forum, there was no need to make this thread.
And because I can't do a post without a smilie, 13.
http://www.killermovies.com/forums/f76/t388403.html
This thread (also pinned) has links to tutorials for various programs, gimp included. The one Barker mentioned is more for peer-advice.
As for being the gimp guru, I've actually been using PS for close to a year now...before that, I had taken gimp farther than most ever do though, so if you have specific questions feel free to PM me. In general though, you just need to read a bunch of tutorials, practice with random functions of the program, and look at good sigmakers on this site for inspiration and guidance.