First thing i want to say is i tested this stuff and it usualy (70% or close to it) works.
1. STAY OUT of dark areas,espically pitch black spots unless u have like 5-6 people with you, or unless you absolutiley HAVE to go through, but still have freinds with you.
2. Try to keep people from wasting ammo, such as if a zombie is darting from a corner and pretending to attack you, and if it seems like its doing that, tell them to stop shooting, but when theres 3-more zombies coming tell them to shoot now!!!
3. Dont go through vents a whole lot, becuase zombies like going through there, and its hard to run or kill, because 1# reason, theyre in single file,and the zombie in front of the zombie is a sheild, same with other members, and #2 a zombie can trap u at entrance when running from other vent entrance *grueling death*
4. Have groups of survivors, preferably 3-4 people to get ammo,escort wounded guy, etc.