Looks really good to me, I can't see anything you couldv'e done differently.
Well that's funny, because I do.
Add more to the bg first of all. The flame would work nicely as a base stock, but there needs to be more to it. Experiment with adjustment layers and more stocks on different blending modes, not just overlay or soft light. Darken, lighten, and exclusion come in handy a lot of times, it's just a matter of playing around and seeing what looks best. Also, I don't know what you did with the text but it's too choppy. You may need to change the anti-aliasing mode. And kill the bevel and outer glow. They just don't look good in sigs.
Overall it's a good start, but you'll get better with more experience.