I announce new posts on Facebook, Google+, and Twitter. I also have a Pinterest account for book covers, etc. Be aware that Facebook rate-limits how many users see page posts. If you "Like" my posts in your Facebook feed, more people will see them; but even then there is no guarantee they will be shown to everyone interested. For a more reliable option, I recommend you subscribe to my mailing list.
I use social media for announcements only, not for any other type of communication. I'm as much of a hermit as I can get away with.