Which Social Media Platforms Should I Use?

I’m trying to decide which social media platforms would be best to use for Skincarebysoleil.com.  Here are the ones I’m contemplating:

Facebook
Google+
Pinterest

Possibly Twitter, Snapchat, and Instagram but I don’t want to spend too much time on multiple platforms.  It would be nice to figure out a way to determine on which platforms the target market is spending the most time on.

Hmmm.