That is exactly what my post was trying to convey. Being in a good defensive spot is where you want to be or quickly get to. Go through the KF levels and every level has one.
Manor - cave directly infront of the dock, biotics - U room, W. london - either in front of the church or in the tunnels with the buses, Wrye, ontop of the fort thing, etc.
I reluctantly agree with ScarFace, that those tried and true spots mean win (though not so sure about the Wyre fort - zombies still climb up and its hard to hit the energizer bunny bloat from hell in the head).
However it gets really boring guys, really. The solution is to play other maps not just the original 5. To get skills that mean you can wander a map while fighting (need a whole team that can do this), and testing out defensive locations. To make my own maps that specifically encourage this playstyle.
The problem is that most people are content to grind the same camp spots over and over, such that they would might as well be playing maps like doom2, defence, doomed. Oh, wait..