If you really want to do well, you should cycle your training, by doing some interval workouts (200s, 400s, 800s) and longer distance runs (4-5 miles). Unfortunately, I don't really know how to set up a program like that, because my coach always set it up for us. I know that the pace (and rests) for the intervals was somehow based on our race day PRs, but I don't know the formulas. Maybe you could find that info on the internet.