Since there is no way to tell if a person is good or bad on sight, kids should be taught to avoid any stranger who tries to engage them. Child abductors and pedophiles are notoriously charming and personable to kids.
The sad fact is, kids trust "nice" adults. So make sure your kids know that "niceness" may be a disguise and remind them to tell a trusted adult anytime they are approached by a stranger.
Common Lures Used by Abductors
Assistance Lure : A man seeks help to find a lost dog, or a motorist asks for directions. These lures work because kids naturally want to be helpful, but kids should know that adult strangers have no right to ask them for this kind of help.
Teach kids that when it comes to strangers, they cannot be helpful and safe at the same time! If kids are approached by a car, they should turn and run the opposite direction as fast as they can--without stopping, talking, explaining, or making eye contact with the driver.
Emergency Lure : This is meant to confuse and worry the child. Someone may tell the child, "Your mom had a car accident and I'm here to take you to the hospital." Or a driver may claim to have the child's father on a cell phone to lure the child to the car. The adult could trick the child by saying he/she is a new neighbor or works for the child's school.
So remind your kids that if they don't know the person's name or recognize their face, this is a stranger! And they should never go with a stranger or walk over to a stranger's car.
Another option is to establish a "family code word". It should be a word that is easy for your child to remember and keep secret. Explain to your child that only adults responsible for them will know this code word (parents, siblings, grandparents, etc) and to never go anywhere with any stranger that doesn't know the code word.
Bribery Lure: It's an old trick, but it still works. A stranger offers children money, candy, video games, or something else appealing to entice them. Teach your children this is bribery, not generosity, and if they go close enough to take gifts from a stranger, they are close enough for the stranger to take them!