Woah I thought you already made more sigs then just one..seeing how long you have been in GFXvoid..

Anyways ---

1) Add a BG. Use brushes and different tones of color to give you the effect that you want!! (Deviantart.com) has some good brush sets..

2) The render looks abit pixelated and low quality. There is also white around the edges.. (gamerenders.com) has good quality game renders. Also if you post a certain amount of times in their forum you get access to Premium Renders Board where you can find awesome renders.

3) Change the text. (dafont.com) has tons of fonts. They also have a whole load of game fonts that could be of some use!!

4) Add a border. A 1 PX Border is what I generally use. It makes the Sig stand out a lil' more.

Hopefully that helped you out dude; by the way that's not bad for a first time siggy!