My advice: Do your very best to sceen what comes through your door (obviously, on an age-appropiate level)and run a tight ship while they’re young.
But once they get a little older-old enough to go behind your back if they want to (this has to do if s/he is old enough, not if s/he is rebellious), its time to TALK TO YOUR KID.
Think about it. They spend their entire early childhood, picking up subtle hints that there are some Big Bag Stuff out there which their parents are hiding from them/protecting them from.
Since you are human, you understand that the curiosity only escalates when they get a little older and have a vague idea of what the Big Bag Stuff is. So, they want to go ahead, and check it out for themselves out of pure curiosity.
Explain, yes-explain to your child what is it that you are trying to protect him/her from. And don’t try to be vague, because at this point they are very curious. Your job is to inform them and eliminate the curiosity.
The older the kid, the more you need to tell them. Exactly. You should tell them what the problem is with XYZ (you fill in the blanks). It needs to be worth their while to struggle with the temptation, and it’s your job to make the repercussions crystal clear, so they should be willing to forgo the short-term pleasure.
So when they are approached by a friend or whoever and invited to join in watching/reading/doing something they shouldn’t. A lot of the curiosity isn’t there. Not all, but a lot.
I WILL say that so much here depends on saying the right thing to your kid. Otherwise you haven’t accomplished anything.
And pray to God that you have instilled in them the necessary values to appreciate your arguments.
And I meant that literally. Go ahead, take a few minutes, and pray to God.