What is the best way to inform a child about such dangers? As soon as my daughter was able to start learning her body parts, she learned where her "private areas" were. I did this in the hopes that it would remove some of the mystery and fascination children tend to apply to the unknown. I also did not want any kind of negative association with these areas. Right along with that went the whole you, me and daddy only business.
I've also told her it's okay to talk to strangers when mommy or daddy are right there with you, but never when you are alone. This stemmed from being in stores where perfectly nice people would say hello or ask her age and she would just stare at me because they were a stranger. So I guess we had to mix in some polite teaching. I felt it was important to start at that time telling her because someone looks nice doesn't mean they are nice and because someone looks scary doesn't mean they are bad. So because you don't know for sure, you shouldn't talk to any stranger when you are alone.
There are also many resources for parents to turn to. One in particular is the
Berenstain Bears Learn About Strangers Book. I feel it gives kids something to focus on (cartoon pictures, characters they know) while you are trying to impart a serious lesson.
Like every other aspect of parenting, it's a tight rope act. It's very difficult to teach children the things they need to know without scaring them away from all the good experiences you want them to have. I frequently feel like a circus performer. I do think it's very important to stay age, or more importantly, maturity appropriate. Very few people besides the parent will be able to decide what that is.
(If you are a parent) How cautious are you, when it comes to protecting your child/ren from potential harm?My daughter is only 4 but already I get anxious about her safety in the future. Hopefully I will be able to temper my own fear and keep her safe while helping her learn to keep herself safe.
I foresee her friends having to come to my house to play just so I can keep my fingernails

and she can interact with other kids outside of school. So, for good of for bad, I think I personally am going to be on the spastic side of protection.