This is very important! And is the main condition for security. If you think that your parents came, before opening the door look out the window or through the peephole to make sure that they are. This rule also applies in the event that the landlord that you are shooting, warned that will go to you. Below are some safety rules:Turn on the alarm and warn parents that she is on!It is not necessary to open the door a man who pretended to be a secret agent. Secret Agent will never come, and will not be knocking on your door. An exception might be if the knock people dressed in police uniforms.Devise a code word, and tell his parents. It could be anything, a relative name, telecast, favorite color, etc. Thus, in the case of an emergency, your parents will be able to send in your house a trusted person and tell him the secret word that you have opened the door for him. Analyzing the password, do not ask a stranger, what is your favorite color (if the secret word - it's your favorite color). So you tell a person what kind you your password. Just ask him for the password. Also, before you let a stranger into the house, contact with parents and specify whether to send them to you with someone.