Often I see guys show up at a track or a field, and do a little jog + few stretches and jump into the sprints/runs, on the typical location on the field/track. Getting yourself ready like that is not only increasing your risk of injury, but the benefit from the workout is not going to be anything near optimal.
1. 30 minute dynamic warm up minimum, anything less and your body isn't loose enough/warm enough nor is your CNS fired up yet.
2. Run with the wind behind you, the goal is running as fast as possible (when training speed), as almost all top sprinters/fast guys do, adjust your position on the field or track so the wind is behind you.
3. Run with your cleats/spikes, not your running shoes! Same reason as above, you want to be going as fast as you can.
4. Make use of static stretches. That's right, static stretches are not the devil they've been made to be for warm ups, as long as they're not actually held that is... All the typical stretches we're familiar with, they're all great to do to increase range of motion at the start of a warm up after a jog, holding them for several reps of just 1 second.
5. Make sure of drills to get elasticity going before doing sprints, incorporate a variety such as high knee skips/runs, butt kicks, straight leg bounds, backward extension run, karoake, etc.
6. Do several sets of speed drills (ex. fast leg) to get your CNS fired up.
7. Do several runs over shorter distances at speeds of 60-80% speed so your body gets preped for the specific task at hand, running.
8. Use leg swings to achieve high range of motion through the hamstrings, hips and glutes. Leg swings are an excellent dynamic stretch.
9. Full recovery between the sprints! Unless you're a distance runner, or a sprinter in GPP, or doing specific RSA workouts, then take full recovery between sprints. General rule of thumg, 1 minute rest per every 10 meters sprinted (ex. 50m sprint = 5 mins rest).
10. Stay warm and loose in between sprints. Don't just stand in one place or sit down, do a couple run offs, a drill, leg swings to stay loose.