Here are a few things to consider if you are serious about this:
1) Why do you want a sponsorship?
2) What types of sponsorship(s) are you thinking would provide you with whatever it is you are looking for (local, national, etc?)
3) THE MOST IMPORTANT: What do you have to offer a potential sponsor? I mean, what is it about you that would be valuable to a potential sponsor? I'm not trying to burst your bubble Ben, but 13 year olds with a handful of inverts and punk attitudes are a dime a dozen in many areas. People think riders get sponsorships simply because they can do a lot of hard tricks, but there usually is more to it. This may be harder to figure out, but take a good look at yourself and what types of things you might be able to do to help promote a company in the public eye and help move product, and then you might be on the right track.
It is always good to get to know the people who run the local shops and put on the local contests, and getting to know your regional product reps is the next step. Also, think beyond the obvious companies. Emily Copeland has a Club Med sponsorship and Leslie Kent was sponsored by Burger King because her father had some corporate ties that got her foot in the door there, but still she had to have something to offer them, do you see what I'm getting at? Years ago, I'm told that Gregg Necrason was offered a sponsorship from local BBQ joint in his neighborhood. I think he decided not to go with it because they wanted him to put a pink pig on his wakeboard or something and I guess he was established enough that he didn't feel it was needed for him at the time, but that was some damn good BBQ for sure!
If you just want free boards and stuff, then I would recommend you keep practicing and start winning your local contests, always maintain a positive public image, and get to know the product reps and other industry players in your area. Good luck with it!