You may get perplexed or nervous during zombie outbreak, but the first and foremost thing you have to do is search for the Zombie Mailman/woman and shoot him or her instantly. Just sit on the rooftop with your loaded gun and take out this nemesis ASAP. Why? Zombie Mailman/woman will be at your doorstep to deliver letters and other zombies will follow him or her. If the zombie saw you placing key under the matt, or witnessed a cat go into a cat flap this could spell trouble. Wherever you this guy, shot him because they will never stop because they are walking machines and shooting of head is the only option.