Every PR person working on book marketing and every author today must understand what works best on social media. Promoting books online is an essential part of a well-rounded campaign, and social media posts are a part of it. Until now, some book industry veterans had been skeptical about the possibilities, but nearly everyone has come on board by now. The degree to which social media can spark book sales depends on many variables, including the size of your following, the book's topic (is it related to your posts?), and how interested your followers are in your posts.
One thing for sure is that it's too late to build a large social media following after you've published your book and are trying to promote it. Another is that testing the hard sell approach and blatantly asking people to buy books rarely works. Instead, it's more about building a following long before your book release and engaging them with posts they find interesting or entertaining. When the online rapport is natural and two-way communication between you and fans is active, you can expect much better results. A few people can post on impulse and have it work well, but most are better off planning.
Social media is also a great extender and lifter of other book marketing campaign elements. For example, if you hold an event, you can post an invitation before and pictures after it. The same holds for media coverage, and you can post links to articles or videos. Most social media followers are interested in knowing more about you and might miss articles or interviews. When you share it with them, the media company also appreciates the plug. Some news websites and TV stations are more interested in authors with large social media followings because they want their stores and shows cross-promoted.
When you plan a marketing campaign, its goal is to reach target readers and sell books. When considering how to do it, a well-planned schedule of posts to coincide with everything else is a wise idea. You can also intersperse posts about other topics of interest so the drumbeat about your book doesn't become overwhelming. If you've been active for some time and have developed a feel for what your followers find interesting and share the most, you already have a head start planning your post topics. Authenticity and considering your audience goes a long way toward making you more popular.