One thing I read and learned earlier in a match was that the longer you sit around the more time you give the 'director' to spawn in more infested and hordes. You have to balance searching an area for health/ammo/explosives and moving quickly along to the safe house. This applies throughout the map and not just the last stand.

I was in a match earlier in which they 3 other guys wanted to fight on the barn roof. They thought they could 'clear' the area.

Also, we should set up some games with 'pistols only' to get those badges.