Essential preparations before you begin
Often overlooked by the beginner, warming-up can reduce the chance that you will pick up an injury and it should be an integral part of your preparation whenever you go out for a run. A typical example would be to walk for 60-90 seconds, building up the pace every ten seconds or so, before breaking into a gentle jog for half a mile (or whenever your body is beginning to warm-up) before stopping and going in to your stretching routine.
Your stretches should cover all the major muscle groups, particularly the legs and back. Do remember to hold each stretch for 10–15 seconds - without bouncing.
Just as important is cooling-down. Once your running distance is complete, you should not just come to a complete stop immediately as this encourages the muscles to contract too quickly and could cause an injury. They should be eased down and stretched out gently.
Correct form once the run is finished, is to drop your speed down to a jog for 30–60 seconds before slowing down to a brisk walk, reducing the speed every 10 seconds or so. You should then stretch all the major muscle groups before you get cold - but this time, they should be held for slightly longer (15-20 seconds), again without bouncing.