However, I've heard all sorts of authors give a litany of what must be done in order to sell books.
On one of the listserves that I'm on, one of the authors is ready to quit writing because of all the things she thinks she must do in order to get people to even notice her books.
I'm going to give you a simple answer of what I think you should do.
Do the things that you enjoy doing and forget the rest.
Yes, unless people know about your book they certainly can't buy it. So you really should do something. What that is should never consume you life. As an author your most important job is writing--so do that first.
When you have extra time, do only those things that you really like to do.
For me, I enjoy Facebook. I like interacting with people, finding out what they are doing and letting them know what I'm up to. I'm a real person just like everyone else--a person who likes to write. Because I like to write, I really want people to read my books and enjoy them.
I also love blogging as you obviously already know if you reading this and are one of my followers. Yes, I promote my books on my blog, but I also promote other authors, give tips on writing, and talk about what I'm doing.
I like doing blog tours too, but I've written about that recently.
Meeting readers in person is also something I enjoy whether it's a book or blog fair, giving a presentation at a library or a bookstore. (I never do regular book signings anymore.)
But--and it's a big but, I love writing the best.
Never let the promotion end of being an author take over your life.