In general be mindful of what information you leave publicly.
@crich makes a good point, profile messages aren’t private.
It’s good practice to delete your pm’s in case you got hacked, it can help protect others information too.
Don’t post others information, if they don’t use their real name don’t mention them by it.
Keep your email secure. There could be something in your pm notification email.
Change your password and use something auto generated.
As a purchaser check their profile, reach out to who gave feedback. Play it slow, a few hours between replies and most scammers will lose interest (more patience for high dollar items). If they start responding like a child in trouble for lying, they’re lying.