Nutrition
The better you eat, the faster you will run. I'm not saying you should try to lose weight -- just that you should focus on healthy foods and water over all other fluids.
You should be drinking water ALL the time. Carry water to class, to practice, to sit on the sofa at night, and aim to drink enough water that your urine is clear. Yes, I know that is awkward, but it is still true. Your goal is to fill your cells with water, something that only happens once you overcome the sodium in your diet.
Milk is great after a run (and yes, chocolate milk really is fantastic after), though NOT before a run unless you want to see it on the side of the course.
Eat before AND after you run. A bagel an hour before, along with a banana and water, will pay off in your race times. After you run you should have some combination of protein and carbohydrates -- you need to regenerate the muscles. And of course...more water or a sports drink!!
Please do NOT eat eggs the morning of a race...they also tend to end up on the side of the course.
Do not get crazy with your food choices during the season. This is not the time to go on a new diet or to try new food choices. And do not try any brand new food the day before or the morning of a race -- you don't want your stomach to be upset while you run!
Carbs should be eaten throughout the week, not just on the day before the race.
Caffeine is a diuretic -- meaning all that water doesn't end up in your cells as you would wish. Please try to avoid caffeine and sugary drinks, as both will sabotage your running plan.