Authors can promote their books through free book reviews, placement on book discovery sites and much more. (bookbaby.com)
I recommend approaching book discovery sites four to six weeks before your promotion, so that you are more likely to get a slot. (feedspot.com)
An example of this is incorporating social book discovery site GoodReads into their complete line of modern Kindle e-Readers, so people can share and discover new e-books together. (goodereader.com)