When running, hold down the run button before you start moving to negate the wind up when starting to run while already walking. By mashing the left and right arrow keys (x and o on the playstation) slightly before a zombie grabs you, you can consistently break out of a grab without taking any damage. On the PC version it can be faster to switch characters by going to the inventory and then switching them from there. This is not possible in the PS vesion. The Dillinger can be used to one hit kill zombies. Let a zombie grab you, shake him off and the shoot it. It will down them in one hit every time.