One thing that seems to sell books is reviews. One way to get them is from book bloggers. Yes, there are bloggers who only review books. You can simply Google “book blogger” plus your genre and find some. Look over some of their previous posts – you want someone who lists positive attributes of books reviewed, not someone you snarkily (is that a word) dismisses each book.
How do you get them to review your book? Most have guidelines listed on their blogs. You follow those guidelines.
Another possible source of reviews are the reviewers on Indie Review. You can research them at http://www.theindieview.com/indie-reviewers/.
You might also find the list of Amazon’s top reviewers useful: http://www.amazon.com/review/top-reviewers
Unfortunately, Amazon does not list the reviewers by genre, though a lot of them seem to review almost everything.
Author Steve Weber has some tips:
Traditional book marketing strategies call for mailing hundreds of copies to reviewers at magazines and newspapers. But for a new author and/or a niche book, chasing print reviews can be little more than a distraction. A better way to launch your campaign is by identifying and contacting 100 to 300 potential online reviewers and sending a copy of your book to each respondent who expresses willingness to look at it and perhaps post an honest critique.
If you spend two or three days contacting about 300 potential Amazon reviewers, you can expect to receive about 40 to 50 responses, and wind up with perhaps 35 reviews, a quite satisfactory result.
http://www.amazon.com/gp/richpub/syltguides/fullview/RNCWTLEMV71VM
Read Weber’s entire article for some good ideas. Weber seems more oriented towards printed books, but I think the same would apply to eBooks. Just ask the reviewer if he or she would rather receive a Kindle or ePub version of the book.
Some authors buy ads on Bookbub and report getting several reviews each time they advertise.
https://www.bookbub.com/partners/pricing
Querying book bloggers is just like querying anyone. Have a good book to promote and write a good query letter.