Talking to small children about "stranger danger"

[giddly]

I've got a 4 yr old DD who as yet I've never talked to about "stranger danger" as she's always with myself or another adult when out and about. Was thinking I would probably need to broach the subject some time soon but having read a bit about it I'm really reluctant to do the "don't talk to strangers" thing as basically we all talk tl strangers all the time (in shops etc.) so it's a really difficult concept for them to grasp in any meaningful way. I remember reading a long while ago on here a thread about an approach where you encourage children to talk to strangers (e.g. shopkeepers etc.) under your supervision and then talk to them (in a low key way) about how it felt to try and develop their instincts for good / bad interactions. I like the idea but is seems a bit heavy, and I wouldn't want to make a big deal of it. What do you all do, and at what age?

bump anyone?

The thing with the "stranger danger" is that it is more likely that it would be someone they know that could abuse/harm/abduct them.

I encourage interaction with others, ie doctors surgery, shops, leisure centre, cafe, library, dentist etc, to build social skills.

I'm just going to teach the "always ask/check with me before you go anywhere", whoever that is, be it neighbour, friend, relative etc.