I've had 2 recent conversations about running faster 5K times, in particular what race strategy to apply.
From painful experience I know how difficult it can be to get the pacing right. In the first mile everyone takes off like a rocket and posts a first mile split that's 10 to 30 seconds too fast, then adjust too much in the second mile, giving back more than was gained from a fast start. By mile 3 your digging up all you have to get to the line and the mile split is usually somewhere in between.
A better strategy is to hold back in mile 1 (hard I know) then to focus on running hard in mile 2, momentum will take care of mile 3.
I use this strategy to good effect in the COC cross country series.