To easily get out of a bad situation. Simply kick the zombies down but it is alot easier if you upgrade your kick all the way. Then you have a small window to kill the zombies while there down or run away if your low on health.
If you are struggling against a horde of zombies, you can climb on top of a car and sit on the roof. From up here, you can kick incoming zombies in the head. It is impossible for them to damage you up here, so be sure to use this technique as a fallback option when the brown stuff hits the fan!