If you play Black Ops 2 you know how hard zombies can be. My most played gamemode is Tranzit and I know how long it takes to master. I have watched multiple videos and played with some experts. This is the technique that worked the most. If you want survive the real zombie apocalypse you should read this article.
Don't start your zombie kill-fest out so quickly. When you start just build the turbine and get out of there. If you can don't kill the first four but do it if you have to. After that get on the bus and buy the gun on the ceiling. Then just ride the bus through the tunnel and to the diner.
Don't get the mystery box unless you get overwhelmed by zombies. Wait at the diner and get the part for the bus in the shed. Stay there and wait until the slaughterbus leaves. Try and get to the third round before you leave. Make sure that when you leave you get on top of the bus if you can. Then head over to the creepy death farm.
When you make it to town you need to get into the bank right away. Throw a grenade at the vault door to go into the vault and then throw another grenade at the vault door inside there and go down the stairs. Stay down there and pack-a-punch your weapons and keep depositing money into the safebox so you can pack-a-punch right away faster next time. Don't worry about not having good weapons. The machine gun and pistol will be enough to last to at least round 20. If you have to use the mystery box at the diner but you won't have to to survive.
I hope this helped you make it farther in zombies and get higher rankings against your friends. If you are tired of playing Black Ops give this game a try.