I run track, and my lifting focuses mostly on explosive Olympic lifts, Clean and jerk, snatch, power/hang cleans, jump squats, push jerk, etc. And building quad strength (Parallel squats, front squats, box squats, hack squats, leg extensions, dead lifts) and plyometrics (box jumps, hurdle drills).
The two components of sprint speed are stride length, and stride turnover (frequency of your strides, comes from quad strength). Work on both, but focus on whichever one needs the most work. For me, that was my flexibility. I had quad strength far beyond most everyone, but I also had the shortest strides. You've probably seen those short stocky guys whose legs are moving a million miles an hour, but they get passed by the tall skinny guy with the long strides. If you want a longer stride, do a ton of stretching, both dynamic and static. Look into the Extreme Stretching routine of DC style Training for a good static stretch. You will also find that working your hip flexors will greatly increase your stride length and speed overall. Running downhill will also help lengthen your stride, and running uphill will increase your quad strength and turnover rate. I would save that stuff for the summer though, wait till the off-season to do your own interval running drills. It's a little too late for that now.
The best thing that you can do right now is start running. Get out running 20+ minutes every day and develop a good base. Nothing too intense, but get your lungs in good shape. I know you're a sprinter and probably thinking that you don't need to run distance, but trust me, it will help you big time when you start doing your in-season workouts. Most guys who don't get in good shape before the season starts don't get anything out of workouts because they are gassed before their legs get a chance to work. The sprint ladders that I assume your coaches will have you doing are not made to work your lungs, they're made to work your legs.
So basically (In order of importance) 1.run, 2.stretch, and 3.lift explosive movements and incorporate plyometrics.
Oh and how old are you? I kind of assumed you were a high school runner.....
I wish I would have taken off-season training more seriously earlier in my career. I didn't really get into it until before my senior year, but that one year still did wonders to my 100, 200 and 400 times.