Here is Part 2 of what Talli Roland told the RNA London chapter about social media.
Amazon - Complete your Author Central page, everywhere. Even the foreign ones, which you can do in English. You can stream videos through the page, and link your blog etc to it. It is good for readership.
Bookbub can be expensive, esp if you write women's fiction. So choose another genre.
Have a newsletter. You can put the link to it in your next book.
Goodreads - Be v careful as an author, esp with reviews. Talli mentioned there had been a well-known chick-lit author who had put a scathing review of another chick-lit author. Not good. Someone said, it might have been Eve Farr, if you don't have anything good to say, don't say anything.
There are other sites you can use; Google+, Instagram (just photos and for a younger demo), Tumblr (microblog, quotes and photos), PInterest (70% women), Klout, which you can put on your followers, what topics you write about and find out what influence you get.
Website. Talli uses Networked blogs.
Youtube - can record book excerpts and blurbs. Stream the video via your Author Central page.
You get out of it what you put in. Awareness = sales. Think global. Be genuine. Have fun.