The Guardian has published a short guide on social media law, albeit it Britain and probably Australia ad Canada (outside Quebec), and it looks valuable, link here.
I think generally the guidelines are true in the U.S. The idea that you would actually be sued for defamation over a retweet sounds remote, but it’s probably possible. The same would apply to uses pictures in tweets and on Facebook or Instagram. But some people are getting more sensitive about photos of them showing up in settings like discos (even if legal) – a trend I’ve noticed since about 2011.
It leads to another article about life without social media. I don’t post my whereabouts in advance and get into the business of inviting people to things online, but to some people this seems like a big deal to join in. Had I become a full time teacher around 2006 or so, I would have closed down my social media and Internet presence entirely for a while. That’s something to explore again.