Replying to NS Runners- How can you get faster?

I am a pretty fast kid and I was thinking about playing track next year. I have played tennis since almost 6th grade but I'm not too good, i'm average but that's not where I want to be. I figured since i'm a fast kid I could run the 100 meter or something like that. A lot of my friends run track and I am a lot faster then them (granted, they are long distance). So anyways if i am going to play track next year, I want to be more then ready. So post any exercises that can help you get faster and increase your agility.

P.S. Yes, I could always google search and I have, but I would much rather have the opinions of fellow NSers.