Conditioning. Lots of it. Practice good form. Time yourself and set goals. Run some shorter lengths at higher speeds and longer lengths at slower speeds, not just whatever distances you compete in. Want it. Really want it and push yourself. Look at other answers too, but these are the most important ones I can think of.
You can run faster in track by identifying the right technique and explosion. You must be explosive enough and then fast out of the blocks. You ought to have some great technique to run or sprint fast times. Check out http://running.about.com/od/howtorun/tp/runfaster.htm for more information.