Before I was published, I relied on word-of-mouth and bookstore browsing to find my reading material. I didn't know book blogs existed until I was published and started looking for outlets to promote my work.
These days, I subscribe to multiple blogs which post reviews and lists of upcoming/recently published books in the genres I like to read (and one or two in genres I don't care for because the bloggers are entertaining). I have bought
many books based off those lists. Once in a blue moon, I will buy one because of the reviews. I still value personal recommendations over lists and reviews.
Sometimes I'll buy one because of all the chatter about it on Twitter and FB (ANGELFALL and Karen Marie Moning's Fever series are good examples of this--the stories were fabulous and I can see why so many readers/bloggers were talking about them).
Never underestimate the power of the book blogger review. Some of my most avid fans who consistently talk up my books (both online and to their friends at conventions or book clubs) are blogger friends who I still have a relationship with to this day, even though some of them aren't blogging anymore. I also have quite a few fans who have followed me because of the guest posts I used to do for bloggers.
What doesn't work is buying a book blog tour where you don't offer anything but a sample of your work or just a book cover or a little "blah-blah-blah" about you. Give the readers of the blog something to think about or something to engage them. Guest posts that entertain (not just hawk you, your writing process, or your book, such as cover reveals or "where you came up with the idea for _____," that sort of thing) and are on blogs that engage their followers are a great way to draw in new readers. The trick is to come up with short and sweet articles readers will
want to read and has some relevance to what you write.
Personally, I started skimming a lot of guest posts in the last couple of years because they felt like rehashes of things I had already read or like they were one big ad instead of an entertaining preview of what the author's work would be like.
There was some information about this subject from a popular YA blogger's
informal survey of their readers in early 2014, along with the conversation that carried on in the comments, that you might find of interest.