What story are you telling? Social media is a chance to tell your story. If you are a band, it is not just about show announcements, downloads, and the occasional hashtag. From the big picture perspective, it is a chance to tell people what you are about, how you are different, and why they might be interested in you and your music.
And if you don't want to bare your soul, if you prefer being mysterious, that's fine. There is a story there as well.