Social marketing serves a lot of different purposes. It's a great way to stay connected with friends and family, or to re-connect with them. It's wonderful for learning more about people, for getting the inside scoop on celebrities and TV shows, it's a great distraction when you want to be entertained. But social media sites are popular, and that makes them good for something else: marketing. As a self-published author, you pretty much need to do it. But as a self-published author, you've got to play to your own strengths.
If you can get a lot of followers on Twitter, you have a great platform from which to tout your books. It's a good idea to post snippets of text, pieces of reviews and parts of your blurb to pique the interest of potential readers. But you can't do that too much, or else you'll be regarded as a spammer.
And it's not really the most effective means of social media marketing, anyway. Social media is supposed to be social, so that's where you've got to put your focus when you want to hawk more books.
Social Social Media
Unless you are already an established personality in some medium, you are not going to build a fan base as a self-published author overnight. It's a very slow and steady process, especially where social media is concerned. The best marketing you can do is to simply be active. Show them you're a real person. Comment on other people's posts, make random comments of your own, give out likes and always respond when someone has something to say to you.