These days authors have to depend more and more on using social media to sell their books. If, like me, you're an independent author, it's crucial... though writers who've had their books published by traditional means also have to reach out to readers. It's especially important if you're only selling your novel as an e-book. Because you can't sell in-person and do readings in bookstores, using sites like Facebook or Twitter is the next best thing.
For F#@! BOMB's release, I've been experimenting with Facebook. We had great success launching LOVE NOTES with a Facebook party, so I hosted aa FB event for F#@! BOMB. I also, of course, posted my book's link on my personal and author pages, and alerted my friends and contacts of its existence. So far, I've sold quite a few through FB, though I'm trying to expand my readership and sales.
I've tried my luck at using Facebook's ad campaigns... and I can't say it's worked too well for me. While most features on FB are still free (and will hopefully stay that way), you can buy ad space to promote a post or particular page. FB has you pay a certain amount of money -- they encourage anything from $5 on -- and the more you pay, the more people you reach. Generally your post/page is boosted for a day or so, or until the money runs out (which happens rather quickly). You can customize your ads to target particular people, which further expands your potential fan base.
FB does what it promises as my pages and posts HAVE gotten many views. I've gotten dozens of "likes" on my author and jewelry designer pages, and have a few new followers. However, while the views are coming in, it doesn't seem like people really click the actual links. People tend to "like" what's right in front of them, whether it's a photo of my jewelry or a blurb about my books, but most haven't bothered to actually head to my Etsy stores or to my Amazon pages. They simply like the post and move on. Sometimes I wonder if they even know what they're liking.
From this experience I've found that it's better to target people who are specifically looking for a product. The FB release parties worked well because book lovers were eager to meet the authors and learn about the novels. They weren't just blindly liking links. I think many of us -- myself included - kind of go through FB and click, click, click, like, like, like whatever pops up... but it takes more effort to actually stop and change the page to view whatever is being sold.
As an online vendor, I'm a big fan of Facebook because it has gotten me book and jewelry sales. But buying ads is not the way to go, at least for me.