rush '15

You sound like you have a pretty good foundation going, so I'm gonna be pretty honest. Be hot. Dress fashionably, do your makeup well, and (for some top tiers) be a good conversationalist. Some tops will take any pretty face and some are a little choosier and would rather take a 9 with a sense of humor than a boring 10.
You mention that you have leadership roles on campus. That's awesome! But I'm guessing that means you're not a freshman, which could also hurt your chances in some cases. Sophomores still have a pretty good shot, but juniors and up almost never get top tier.