We love books, so we started with the oldie, "The Berenstain Bears Learn About Strangers". There are many more books out there, this was just one that we had at home about strangers. Next time we are at the library, I plan on looking for a more udpated stranger book to check out as a refresher for her.
I didn't want to overload her with information, so we did the 6 pages over two different days, about a week apart.
Lastly, a couple days after we finished the pages we did some roleplay in the Living Room. Daddy would pretend to be a stranger and at first, she did make some mistakes, but she learned very quickly.
The main rules (reworded by us) that we talked about with our daughter were:
1. Who is a stranger? Anyone you don't know.
2. What adults do you trust? Police, family and teachers.
3. What do you do if a stranger tries to grab you? Run away and scream. If they do grab you? Bite them.
4. Always play with a friend.
5. Don't talk to strangers.
6. Dont' get in cars with strangers.