You said this is your first sig so ill have this to say..
It looks nice but could be alot better with little touches of improvement.
For example:
You have the outer glow around some layers as the stock yellow that is by default. Try messing with the colors of that glow to make thing seem more blended. Maybe a darker color would work and give it some depth perhaps. Also a big thing for me seeing this was the size of the sig. Halomods says sigs 120x500 but you can go smaller to obtain a better effect. Maybe if you slid Rodney over to the left so he partially behind his name and cropped off the excess to the right I feel the sig would be less "open" with "dead space". take the slogan of "god on wheels" and place it under his name centered perhaps and bring the opacity down on it some also. One final thing to try would be reducing the brightness on Rodney himself and adding a slight touch of contrast to him.
For a first sig I think its awesome. All the basic functions are represented in the sig meaning it has layers, you can cut out image effectively and you didnt use Halo font

. Just keep at it and try those things I mentioned. Im sure by tinkering with thoes settings your going to find other things as well to make it even better then ever.
GJ and I always pick Rodney Mullen when playing any Tony Hawk game. Hell, he was good enough to do Christian Slaters freestyle skating in Gleaming The Cube so that has to say something about him
EDIT:
This post was made in referance to V1.