Fartlek - "speed play". Fartlek is one of the best ways to increase your running speed. It's very effective. I do fartlek 2 time a week. So, how does it work?
You can decide how to do fartlek, there are 3 different ways to do it:
Don't run those faster sessions as fast as you can. You should use 60-80% of your power.
Here's a simple example how you can do your fartlek training:
You can always improvise. As much as you can. Just listen to your body. Maybe in the beginning try just one such session. Later you will be able to do 2-3 such sessions. And believe me, it really helps to increase your speed.
It's very good when you finish your last fast distance, you still have 1-2 miles to run home. Do not finish your last session at your door. Give some time for your body to recover.
It's very good to do such session for a particular distance, but to do this it's the best to go to a stadion, it will be much more easy to know how much meters are you running.
If you decide to run uphill, find one which is 100-200 meters length. When just run up faster and very slowly run down and do it as much as you feel it's good for you.
I hope it was helpful and keep running.