Link all the teleporters as soon ad possible and go to magic box. Get decent weapons and go to the teleporters behind the power. To the right of it you can go underground. One person take the window under there, perhaps th one with the worst weapons. Until round 25 someone take the window up on the balcony. After that save one at the window so everyone can get perks an upgrade the weapons. On the later levels, retreat into the tunnel for cover. So on dog rounds, there is a glitch in the tunnel to use.

If all else fails, run fo your life teleportinf whenever you can