Find stretches you like and that seem to feel worthwhile. If you do stretches you don't like or seem useless, you will soon stop stretching all together. Stretching is personal, some people need a lot, some almost none at all. You must decide. Minimally you should stretch your hamstrings, groin calves and hips. I personally do these stretches and they take about 2 minutes. Lots of stretching books out there if you want diagrams, Anderson's book is probably the biggest seller.

Warm Up Cool Down

Start all runs slow for the first half mile or so. Finish all runs slow for the last mile. Running hard down the home stretch might impress the neighbors but is detrimental to recovery. If you like to run hard at the end of a workout, do it in the second to last mile, then run home slowly. Lactic acid build-up from the sprint to the finish leaves legs dead for the next day's run. Remember to do a cool down run after all races, even if you feel terrible and slow. You'll appreciate it the next day. When stopping exercise suddenly there is an increased risk of heart attack for those who are prone to it.

Finish slow dangit.