You can move around inside your barricade, aim (head shots work well) and shoot your weapon. Once they get close enough, you should use the chainsaw.
Spend more time looking for survivors at first (8-4 survivors to weapons). Then switch the amount. Otherwise you won't get past day 2. Try not to aim for the chest when taking down zombies. That does the least damage. The closer they get, the better your aim, but it's not worth the wait. Even if you don't get a weapon when searching, the time still counts.
I played this game a while ago, but was amazed to see I never did a review of it. So here you go. Play the Last Stand at kongregate.