Be careful not to shoot your allies--it is not worth killing two zombies if you have to down an ally to do it. Do not bother searching for items as the longer you linger, the more zombies will spawn. However, if you see something along the way, feel free to pick it up. If someone gets pinned or grabbed by a Smoker, sometimes it is easier to free them by just going up to them and pressing LT. Most people think you need to run from the Tank, but even under the Easy and Normal difficulties you must to kill two Tanks before the rescue vehicle arrives. Therefore, it is not possible to run all the way back to the safe room. The easiest way to kill the Tank is to have everyone fire at it while the person it is after tries to dodge and fire at the same time. Even under the Expert difficulty setting it should not live more than a minute if everyone calmly shoots at it. There is no way to pass the Tank without shooting it.