I'm not going to claim to be the omniscient runner, but I do run a 15:50 3 mile so I think I am qualified to speak about training. I'm not sure what kind of training you're doing right now in terms of miles/week and days running per week, but you gotta start somewhere. I would start out running 4 days per week @ 15 miles per week. Do this at whatever speed you wish and whatever mileage spread you wish. One of these days do a speed workout meaning go to the track and do 4x1000 meter repeats or 800m, 1000m, 1200m, 1000m, 800m. You can choose your own workouts, find some online or ask me via email or the thread, but whichever ones you choose you have to be going hard at them since your base mileage (your other runs during the week) are going to be at a normal pace. Increase your mileage no more than 20% per week. Eventually you will be able to run 6 days a week and when you this you should do two speed workouts a week, maybe 3. I would work up until you're doing 35-40 miles a week with 2 or 3 speed workouts, remember your base mileage is just at a comfortable consistent pace. Test your 3 mile time once every other week, you will see improvement after two weeks, i guarantee it.
I run the mile for BU track and the 8k for the xc team. Just to give you an example I'll give you my ideal week of training (it's hard to do this sometimes because it wears me down fast), but here it is.
Monday: long day. 13-15 miles with a 20 min tempo run in the middle (6 min pace for tempo). The long run is what really gave me a jump in my running, made me very strong, but don't do it until your body is absolutely ready for it.
Tuesday: Easy 7 or 8 miles. 7 min. pace.
Wednesday: Track workout. 3 mile warmup. 8x400m at 63 seconds. 3 mile cool down. 10 miles total however i can get it.
Thursday: 10 mile, decent pace (6:45)
Friday: 7 miles very easy (7:30)
Saturday: Race (you can make this your practice pft). Try to get 10-12 miles for the day after race and 3 mile warmup.
Sunday: 8-9 easy depending how legs are feeling.
My ideal mileage is 70/week, but sometimes my body breaks if i consistently do that, others on my team can handle even higher mileage. I never recommend running 7 days/week unless its under the instruction of a coach and you have teammates or friends to run with. Most importantly, never go beyond what you know your legs can handle (in terms of injury), your body will break. Also, nutrition is essential to running, although I find it to be the hardest part. As long as you're getting plenty of protein and the essential nutrients, the lighter you are the better. If someone has good advice on nutrition please post it because i could use it. Hope this all helps, just some advice from a collegiate runner/Marine option midshipman. Any questions let me know, I'd be willing to give some more personalized advice if you want. Also, this is just advice, please disregard if you'd like.
Pat