1: The first thing you want to do when the game starts is to sprint to a window.
Don't bother to get a gun. Just go with a pistol. Always shoot at their heads because if you don't I'm pretty sure that is a waste of bullets.
2: And the second thing you want to do is heal your bros every time when the round is over. Because if you don't a zombie/stinker will sneak up to you and take you down.