This is my survival guide version 2 for Nacht der Untoten, as my last submission didn't quite include everything. Hope it helps...

Stay in the first room until round 3 for beginners, 4 for pros, and 6 for champions, and this way you will keep the amount of zombies spawning at a controlled number. Buy a M1A1 carbine at round 4 if you are a beginner, 5 if you are pro, and a kar98k at round 3-4 if you are a champion. This will help you save points.

Do not forget points are precious, as they help you to survive, so dont go off and waste them. Remember that.
You must go to Help first (It looks it says HELL but everyone knows it says help). Use this tip: one person guards the door, one guards the wall, one guards the far barrier, and the last player guards the last barrier. Stay there until the rounds start getting really heavy and difficult. When this happens, open the stairs in HELL, and camp by the steel hand grenades.

Use grenades wisely, as you are limited to holding 4 at a time, although there are grenades behind you. But dont forget, they cost 250pts. Dosent sound expensive, but think about buying it 4 times - thats 1000pts spent on grenades! If you have rubbish guns while by the grenades, either: 1. Buy the sawed off double barreled shotgun, or 2. At the end of the round, go to the random box.

If you are on multiplayer, I like to perform this trick: When someone gets downed and needs reviving, get everyone to guard him while you revive him. Make sure there is someone guarding every place, or zombies will barge in, eat you and go for the other players.

Over my past few co-operative matches on zombies, Ive discovered the zombies go for the player with the most rubbish weapons. So always guard each other at all times.

When on a high round (eg round 15) always stick together and guard each other, otherwise one will go off and accidentally get downed, then another player tries to revive him, but he gets downed too, and so on until game over.