However you fancy yourself as a runner, it helps to vary the activity and output you're doing on a weekly basis. Increased speed, strength, and endurance are the aim of this guide.
One thing that's incredibly important is the adoption of a dynamic warmup predicting intense exercise - static stretching before workouts weakens your muscles and reduces max output.
3-5 minutes of light jogging (40-50% max) + 20 yards of...heel kicks (x3), knee ups (x2), sidestep (both ways x2), backwards jog, open the gate leg outs, close the gate leg ins, hamstring kicks (x2).
Open the gate = knee at 45 degree angle, raised up and brought in-to-out, as if you were stepping over something. Close the gate = opposite...out to in.
Timed 400s. Running at 80% for 400m. 30 second break between each 400 interval. Aim to get within 3 seconds of the first lap's time. Repeat x6. Then rest for 3-5 minutes and rehydrate (water!).
100yd ramp x3. Hopefully your track has a marked football field. If not, approximate using the 100m straights on the track itself. Start at 1yd line, sprint+reach max speed at 50yd > 100yd. Jog back.
Timed 800s. Similar to timed 400m intervals, except your rest period should be 50% of your final 800m time (eg- 3 minutes, rest for 1:30). Repeat x2 before heading into cool down.
Cooling down. After your final rest period following your last 800, jog at 40% for two laps. Repeat dynamic stretches for tight muscle groups then engage in static stretching. Hold stretches for 20s!
It's a long road, but give it a try! Varied workouts increase performance - but you need to let your body rest. Don't overdo it and be patient :)
Don't forget! Proper sleep patterns and a healthy balanced diet go a long way. Good luck and listen to your body!