Like many authors of published novels, I long to able to do what I do best, which is to simply write fiction.
But genre fiction --be it, SF, crime, romance or westerns-- is a complex result of artistic and commercial prerogatives. So as a commercial writer I must and willingly do promote my works. I have a great deal of sympathy with the colleague who says that she has no time for social networking, and she's going to concentrate on writing and leave it to the reviews of her works to sell the books.
Good idea.
Except that sometimes your work won't get reviewed. There are 60,000 books published each year. Not all books get reviewed, or the reviews are mixed or even negative.
In that event, every author needs a Plan B. Or even a Plan C.
One method is to promote in person. Whether it is at conventions, or at your local library, or your local bookstore. In that event, practice your reading skills; produce chapbooks - little A5 booklets of four or eight pages of extracts of your work.
Another method is promoting via blogs. Many writers such as Nikki Leigh specialize in producing blog tours, whereby writers can promote via other writer's blogs.
A longer term method is to promote via social networks such as Facebook, MySpace, GoodReads, and so on. These are for longer term promotions, building the writer as brand, rather than the book in question. But their benefit is that they require only a few minutes a day if the writer is busy.
They're a little like going for a walk and chatting to people that you pass in the street. A quick 'how are you?' (the caveat is that it needs to be genuine!) will achieve more than hours of posting 'buy my book!' and will be less off-putting.
So if you're a starting author, think about how you want to approach promoting your work. But don't ignore it and assume that your book will sell itself. That way lies disappointment.