How do you teach your child about strangers? How is it done, but not to the extreme?

I ask this b/c I brought up a childhood store where I would buy penny candy. Now my incedent was not at that store, but another one. I was about 12-13y/o. One morning my girlfriend who spent the night as we lived in a duplex next to each other, decided one morning to walk down to the Dairy Mart for breakfast. If you don't know what Dairy Mart is, it is like a 7 eleven w/o the gas.  So we get up and it must be 7-8am, and grab my dog. (Doberman) We get there with no issues, but as we are looking around the store a man comes up to me and informs me there is someone in this white truck/van that I knew, and I should go say Hi to them. I looked over the isle and told the guy I didn't see anyone I knew. Again he tells me come on out and say Hi. The lady at the register then came up and told the guy he would need to stop harrassing us, or she was going to call the cops. Well he left, and she still called the cops. Thank God, or someone or something that I did not go out there. Thankfully my Mom taught me about strangers, etc. The cop offered us a ride back home but we declined. I had my dog with me and was not leaving him behind. Plus what would my Mom think as I rolled up to the front of the house in a cop car?!?! I believe the cop followed behind us as we walked home. 

So not to  but make sure your kids know about strangers.

I too was molested by someone I knew.
But, it is important for children to be taught to respect the fear of strangers.  To never get in a car with someone they didn't know for instance

That's freaky!! I remember being told to never get in a car with a stranger, even if it was someone I knew that had worked for my father, unless my father was with them of course, and once in awhile there would be someone on the farm that my father would warn me he didn't want me off alone anywhere with them.

I've had the talk with Eli about never getting into cars with strangers awhile back when there was a car pursuing 3 towns, one being ours, and he was going after girls, but still. Thankfully the girls were all very smart and ended up getting really good descriptions of him and he was caught. He understands that I believe. I've also chatted with him about if he ever were to get lost, in a store to find "the payer lady" (cashier...that's what he calls them) and not to talk to anyone but the payer lady and tell them he's lost, never leave the store, never go into the bathroom with anyone but mommy, etc.
That confused him a little because cashiers are strangers. Ugh. But I figure if we keep talking about safe strangers and not safe strangers eventually it will sink in.
When I was 4 (nearly 5) I got lost at a rodeo in Florida on vacation, but I had my wits to find a policeman that I knew I had seen on my way out of the stands. I hope Eli would to.

There are so many diffferent scenerios out there, and it could be a woman that looks nice and pretty or alittle ol'lady that is lost or whatever! I just say don't go any where with any one you don't know..stay in the shop etc...and find a security guard/police or shop keeper to help out. neighbour..i'm really paranoid and its my biggest fear...I worry over sleepovers but try to give my eldest the space she needs to grow.
 I always talk about stranger danger..good bad touch..

My 4 year old is having a hard time understanding why we wouldn't want to help the nice old lady looking for her dog, or the man offering her candy. She looks at me and said but Mom they might be NICE. UGH!!! Praying that she will just scream and run if ever encountered, but she is just such a sweet girl. Hopefully she is never approached!!!!! I am trying to get the seriousness of the situation across without freaking her out. It's a hard topic!