Before we jump onto a social platform we need to flesh out a couple key questions. First and foremost we need to identify your goals:
Are you trying to communicate with multitude on events/news Do you want to promote tourism Do you want to drive attendance/sales/awareness
Hopefully you have a basic understanding as to who your target demographic is. After you have identified that, look at the demographics for the different platforms to determine best fit.
A question to consider that is largely ignored is, do you have the ability to use the platform correctly?
-Twitter requires volume of short content -Instagram needs good quality photos -Pinterest requires content be relevant and useful for audience
Understand to really succeed you need to adopt 2-3 of these platforms, as a minimum. As a direct result, getting on social media is going to require a fair amount of time to monitor closely and continue to develop strategy.