There’s a new article that seems to be making the rounds, gathering shares and likes, entitled How to Tell a Great Lie as a Parent. I suppose the short version of this post is, "You Can't", but you can read more for details.
It's horribly important to talk to your kids in an age appropriate manner, about bad touches and bad secrets, but that's not enough. My parents did that, and did it very well... Most victims don't tell because they are afraid, afraid of the consequences of telling.