Practice what you preach.

I was at a barbeque last night, and was running around with my daughter. We saw a bug, so I reached down to pick it up and show it to her. She is not afraid of bugs. She's actually pretty fascinated by them. So I showed it to her and the other kids, and let it go. Later on I found a toad. I once again picked it up, to the protests of my wife, saying it would pee on me. I showed it to the kids and told them not to pick it up.
Of course the irony of this is that the first thing they will probably do, specially my daughter, is pick one up.
Kids, and adults for that matter, follow examples, not words. One of the main issues many people had with the Crocodile Hunter (RIP) was that he had to touch everything. Of course he would tell those at home not to grab animals, but he did so while holding one. So what did kids want to do? Be like the Croc Hunter, and off into the woods they'd go, looking for snakes to grab. This is how they get hurt. It was a small lesson I learned last night, but a very important one. If you don't want kids to touch something, do something, or go somewhere, you need to practice what you preach. I would really have no legs to stand on if my daughter got stung by a wasp and I asked her why she was playing with them.
"You play with bugs all the time!!"
Practice what you preach.