For this you will need to complete days 1-55. There's not much i can say but here's a few tips.
-Use teddy bear's wisely! you only get one everyday or an extra for rescuing a survivor. All you do is press RB or LB to throw it then the zombies gather around it and it blows up. (Similar to the pipe bomb in Left 4 Dead)
-KEEP MOVING! You will need to stay on the move, especially as you progress farther into the game. If there's a load of zombie's around you try to use your chainsaw by holding RT. (I wouldn't Suggest using execution mode with LT)
-Pick up different guns, the M16 you start with is great and has infinite ammo but, it's not as effective as the Shotgun, SMGs, Hunting Rifle, Rocket Launcher, Etc. (Wouldn't suggest getting Molotov's unless there's tons of zombies around)
-Steer clear of the Birds/Bugs or whatever you want to call them that the queen makes, they take you out for good once they get you. Also be aware of Big Boys, Granny's Knives, and stay as far back as possible from the sheriffs.
-For the Boss battles aim for the center of him and watch out for lazers, birds/bugs, and his claw traps.
I hope these small tips helped and good luck!