1. Slow Cadence
Running speed is a result of stride length multiplied by stride frequency. That said, many runners will first attempt to increase stride length, which in turn reduces their stride frequency, which, under optimal conditions should be around 180 foot strikes per minute. The easiest way to count stride frequency is to count your steps for 15 seconds and multiply by 4. If you count 40 steps in 15 seconds of running–meaning your are currently taking 160 foot strikes per minute–gradually make the jump to 180 foot strikes per minute by focusing on increasing your turnover.
Take a few minutes to listen to your feet hit the pavement when you run. The more time your feet spend on the ground, the more energy is required to propel it forward. Focus on increasing your cadence, and in turn, your efficiency.