Whenever someone I know starts telling a story that involves sharing someone else's personal information -- medical, emotional, relationship, whatever -- I make a mental note to try not to share any of my personal stuff with them.
Trustworthiness is modeled.
@starkatt I know this is an area in which I've failed before. Thank you for the reminder. It's worth bearing in mind, especially online.
I've also been known to ask "am I supposed to know that?" in response to certain kinds of personal information being shared.
I'm not perfect at infosec myself, certainly, but trying is important.