Simple advice, make a spreadsheet
Five years ago, the first few weeks with a new client would’ve been spent interviewing key staff members and stakeholders, reviewing all the marketing materials, and planning solid communications strategy.
Flash forward a few short years.
The first few days (at least) are spent helping them access all the social media networks that they’ve had various staff members create accounts with. “We had XXX sign up for all these so that we wouldn’t miss the opportunity, and he/she was young and understood more about it than us.” Now, there’s incorrect information dispersed throughout the web and nobody knows how to kill that MySpace page showing pictures of things you wish nobody had ever seen.
Somewhere, somehow, store a copy of all the social media accounts you sign up for. Keep a record of the simple things, like the email address used to recover and reset the password. It’s going to save a lot of pain, somewhere down the road, even if you think you aren’t headed down that road.