When someone knocks at your door, acknowledge you are home. Talk through the door without opening it. If you don't answer, and it happens to be a criminal type, they may attempt to break into your home.
You are not obligated to open the door to anyone. Identification should always be verified before opening the door. A wide angle door viewer is an absolute must if visibility of callers is not possible. Service representatives should have appointments and not just "show up" at your door.
Do not rely on a door chain for security. Partially opening a door equipped with a door chain is a practice which must be discourage. The door is not secured. A door chain cannot withstand physical force.
1. First, talk to the person through the door. You don't know the person, so don't open the door!
2. Ask what they need. If it is a car problem, offer to call their road service for them. If it is an accident, call 9-1-1 for them. The idea is to keep them outside and you make the call for them. The police are very helpful. There is a chance that it is legitimate and a chance that they may be scamming you. So protect yourself first.
3. Ask them to stand by while you place the call. If the person(s) stays, it is a good chance that they are legitimate, however, if they leave quickly, it is probably a con.
Suggestion: Take a good look at their face, clothing, any distinguishing features, direction of travel, another person, a vehicle, etc. This may be useful if you call the police for help.
If the person leaves quickly, it is considered very suspicious and it would be best to call the police department immediately to report it. Call 9-1-1
#2
THINGS TO WATCH OUT FOR THAT ARE NOT SO OBVIOUS:
Strangers and solicitors.
Verify the employment of all solicitors, meter readers and repair personnel prior to allowing them entry into your home. This can be done by obtaining the employer’s number from the telephone book or by contacting directory assistance. Never take a telephone number offered by a suspicious person. Be suspicious of alleged delivery personnel with a wrong address or asking if someone lives there.