Teach your child to recognize danger: who, what and where.
Tawfique Al Tazim
What: Adults do not ask children for help. That should be a warning sign that something is wrong. Your children should also be aware of anybody who asks them to get in a car or go somewhere with them, or anyone who crosses a boundary, such as touching them or invading their personal space. Teach your child to not give people the benefit of the doubt. Instead, teach your child to gather information and trust his or her instincts.
Where: If someone asks your child to go to a second location, that should set bells off in his or her head. If your child is alone and an adult approaches him or her, that is not a good sign.
The Buddy System: Kids should never be alone, even for a minute. They should always be with a friend or two, because there is strength in numbers.
React: Children must also know that it is OK for them to say no. They shouldn't worry about being polite. If the feel they are in danger or something is not right, they should move in the opposite direction, yell, scream and ask for help. Rehearse this with your children by asking them how they would react in certain situations. Don't tell them how to react. For example, ask them what they would do if they are at bus stop and a car pulls up offering a ride.
Communicate: It's imperative that you establish a line of communication with your kids about anything they don't feel comfortable talking about.
From:http://drphil.com/articles/article/623