As the mother of a 53yr old, all I can tell you is my approach.
As a young child I encouraged my daughter to talk openly with me, as I did with her. I would advise her how to handle situations (fall outs with friends and other more important things.). But I would never insist she followed my advice.
As she got older, we had a mantra "if you think you are old enough to do it, you are old enough to tell me you are going to do it". The opposite, of course, was also true. If you are too afraid to tell me what you are going to do, that should tell you something important.
When she went to university, I told her never, ever to buy drugs from people she didn't know, because you never, ever know what those drugs are cut with (and also never to get into rounds with people if you couldn't stand your corner).
She tried drugs, of course, a bit of blow, a few Es. But she was safe, didn't get into the hard other stuff. I was lucky.
But I wasn't going to sit there with a G&T in my hand and give her a lecture on the evils of drugs.
On the whole, I'd say she/I were very lucky. But I'm pretty sure most of that luck was laid down when she was a child, and she knew she could, and did, talk to me about anything, without fear of judgement.