Running speed is critical in many sports....some are born with more speed than others...One fact is true: you can improve your running speed no matter who you are!
The running mechanics are important to improve straight-ahead speed. Practice these mechanics every day! Strengthening your body (core included) will also help make you faster.
This may sound elementary (and it is) but pump your arms as fast as you can (with control) when you run. If I see 10 athletes run on a given day, chances are that all 10 will not be pumping their arms correctly. And, some will not be pumping their arms at all! Pumping your arms allows you to use your upper body to run faster with more power. And, when you get tired, pumping your arms can help you maintain your speed.
Use your shoulders (and not the elbows) to pump your arms as fast as possible. Your hands should be relaxed in unballed fists with the front hand rising up to about nose level and the back hand passing the buttocks. Move each arm as one piece with the elbow bent at 90 degrees. Arm action should be straight forward, up and down and never flailing side to side.
Many times, its practicing the "little things" that make you better!