I can go on all day, but the most persuasive voice is your own. Imagine yourself posting your address, full legal name, social security number and bank account numbers right here, right now. What are some considerations that would prevent you from doing this? Would you attach the same information to political activism? What if the tables were to turn in the future, leaving you on the wrong side of history and consequently out of a job?
1) set up a facebook profile with a sock puppet identity. make your character female and ~12-15 years of age. don't forget a profile pic.
2) prepare your inbox.
https://www.frc.org/updatearticle/20191216/posing-online
most people don't have this conversation with their kids. they let them sign up and hope for the best. (which 12 yro doesn't have a phoen today??) -> that's what I'd consider extreme (not somebody teaching their kids about how to be safe).
Parent’s response seems more oriented around the, “saying something you regret on a permanent record” area which, again is a legitimate concern, but not what I would classify as “basic safety.”