When you are playing as the zombies on quarantine mode to avoid knockback from bullets just crouch and you wont budge (p. s . You have to stay still for it to work).
Commander Of The Army
Play the game a LOT and your EXP will go up and
eventually you will become commander of the army,
the highest rank possible in the game! Note:
when you buy guns look at their damage meter. It
will help a lot.
Dont Be A Tricked
Don't be tricked by a guns stats. Some guns have the same stats but they are actually different. Looks can be decieving.
In quarintine mode bring a heavy machingun into the fight and if you can also bring a flamethrower and bring either smoke or incendery grenades.