As someone who'd ever experienced that type of shit, my advise is, do not form any relationship when both parties aren't ready to shares the excitement of being in love but lives apart physically. That magical experience were not for everyone. Need a two very loving-loyal person to make that relationship works and also a lot of efforts and commitment.
But if it's just a casual shit, meh, just do it, being young and reckless are part of living life to the fullest. Some lessons need to be learned by experiencing it yourself I tell ya!
Spoiler: you can't. Nowadays it's just a source of scams, you either deceive or be deceived. A different thing would be an arranged marriage through a well-reputated agency, otherwise it can only get worse.
But Sensei, are you actually aware that youngsters nowadays cannot be told to don't do this or do that? Let's the youngsters living and experiencing some shit by themselves, cuz... Without experience it by themselves, they won't know the lesson of it~