One thing you should consider before posting: When you make something publicly available on the Internet, it becomes practically impossible to take down all copies of it. --Tumblr Terms of Service
Instagram, Facebook, and Google have all recently been involved in lawsuits relating to privacy. If you manage the social media for your organization or have a general interest in your rights as a user, it is recommended that your familiarize yourself with the various ToS documents. You should also do at least one Google search for each network and see what people are saying about changes within the past 6 months; there are usually tips and tactics in online forums that can assist your social media marketing. Terms of Service are fluid documents that change regularly, so be on the look-out for alterations that affect you and your organization.
Some social media website terms of service:
Facebook Terms of Service (Here’s an extra treat for learning how to use Facebook’s Brand Assets)