There seems to be a generally well agreed upon method for promoting events on social media. Take a gander at the following resources and notice what they have in common, which strategies stand out to you, and make a decision on how you want to proceed:
How to Promote Your Business Events on Facebook (Forbes)
How to Promote Events via Facebook (performancing.com)
How to promote your company’s event on social media in 10 steps (bizjournals.com)
How to Promote Your Event on Facebook (flyte.biz)
HOW TO: Plan and Promote Events With Social Media (Mashable)
Add any good resources in the comments!