Social Media Presence
This one's for the millennials. Don't judge him or her if they're super not into Instagram and aren't posting about/with you constantly. Social media is not everyone's thing and if they're a little "old-fashioned" (lol) and like to keep some things private, let them. I mean, if they claim to not be on any social media whatsoever, run.
[Photo via @talitavon]