*** Of course, just running as hard as you can should do it! But if it were only that simple you could do that week after week and continue to improve. You could still get a PB and not run at your best or you could run at your best and not get a PB. Certainly giving it 100% gives you the best chance. Of course.
All the suggestions are starred:
*** 3 stars. IMHO it will work
** 2 stars. It might work
* 1 star. Can’t hurt
X 1 cross. It CAN hurt if done wrong.
All 50 tips are shown here as a series of posts : http://the5krunner.com/tag/how-to-get-a-5k-pb/ or on twitter using #howtogeta5kpb. They are all SHORT-TERM tips that will work in the next week or so with varying degrees of success.