here is some hints
Remember the zombies simply take the shortest distance between them and you use this to your advantage.
Example if you choose to open the red door and the staircase to the upper level from the weapon chest room, one person should be in the weapon chest room two in the grenade room and one at the far end window of the first floor above the Tommy gun location this will confuse most of the zombies they will stay in the centre between all four players and run in a circle as long as someone keeps drawing them.
Zombies go down faster by taking their heads off but some will survive being headless so aim at the neck this reduces headless zombies as you?re shooting both the heads and torsos.
Don?t kill the last zombie at the end of rounds instead use the time to board up windows, reload and renew weapons.
When standing together
Fire in twos when zombies come from one direction don?t all shoot the same zombies together if everyone runs out of ammo at the same time in a confined space like the grenade room there will be virtually no chance of survival as tens of zombies crash the room.
In the room with the weapons chest stand beside the staircase railing zombies will stop on the staircase and attack you giving your team mates more time to obliterate them on the stair case.
When sprinting before doing so switch to a light weapon for example if you have a bowling and a tommy gun use the tommy this way running will be faster and more easy then carrying the bowling then switch back.
auto head shots
with auto aim enabled using a shot gun jump and aim at zombie heads but this is probably not so useful just a stunt.
At the weapons chest hold square when the question mark (?) turns dark to get the ray gun or next most powerful weapon.
One of the best tips of them all is to disable the aim assist because this causes a deadly glitch in close combat with the zombies. With the aim assist disabled you will have more control and your character will no longer aim at the floor or automatically commit suicide.
Know the roles of a game and you will see how to take advantage of them to bend them the way you want, this is not cheating as you are not breaking any roles at all, you are still following them the ones others don?t see.