how many miles do you run per week?
if you've been doing the "sprinter's workouts", you probably aren't getting enough mileage.
this is especially important for the 1600-3200, but even the 800 is half speed-half distance. It's that weird distance that's too short for many distance runner and too long for many sprinters - and it might be one of the most painful races (at least it was for me).
ideally, you should be getting at least 30-40 miles per week (especially if you want good 1600-3200 times) - that's what I did in HS, and in college it was 50+ -- many people do even more. But if you haven't done much mileage, you'll need to start with no more than 2-3 miles per day, along with a longer run of 5+ miles once a week. Most of the daily runs (including the longer run) should be at a relatively easy pace. On a couple of the days, run the last mile or two (or more) at a brisker pace. Once the season starts and you're doing workouts and competing, you should gradually cut back on some of the distance runs, especially if you're feeling "dead legs" or "burnt out".
race-specific training should focus around your race pace - do these a 2-3 times a week after a few weeks of distance running.
the core concept is the even pace workout - for the 800, you'd divide the race into 4 reps of 200 (maybe throw in a couple more if you can maintain the pace) - and run each 200 at race pace with a short recovery in between (say 10-15 seconds) - when doing this type of workout, each rep will feel very similar to what a race would feel like at that stage - the first rep will feel really easy, and the last one will feel really hard - and then after the same short recovery, you run another rep (if you can).
During this workout, you want to concentrate on maintaining the same pace - and focus on how you feel - remember how easy that first 200 feels - and then focus on how much harder it gets on the 2nd and 3rd 200s - and the last one should feel like you're doing an all out kick to the finish line. You can imagine you're actually running a big race and how you're gaining on everyone and then sprinting by them at the end.
Earlier in the season, you're focusing on building up your stamina - so you'll also want to do workouts where the pace is a bit slower with more reps. You might do even-pace workouts based on 1600m or 3200m race pace & distance.
Later in the season, you're focusing on getting faster - so you'll want to do workouts slightly faster than race pace, but with more recovery allowed in between. This gets your legs used to going at a faster pace.
The ideal workout should leave you feeling tired, but not totally exhausted. If you find that your times are getting slower, or your legs feel really heavy, or your feeling like you're about to catch a cold, or if you suddenly have "no motivation", you should cut back a little. This is especially important if you haven't done much distance training during the winter. Overtraining can be just as bad as undertraining. You should take a day off each week (or run really easy)
At end of the season, when the biggest meets are occurring, you enter the "tapering phase" where you reduce the level of your training for a week or so, allowing your body to fully recover from the rigors of a season's worth of training and racing. Workouts might consist mainly of running a few easy miles with a few short wind-sprints thrown in - or a few race-pace 200s with full recovery - just enough to keep you sharp, but not enough to make you tired.
Good luck -- and hope you have as much fun as I did