Another valuable source of potential reviewers is people who've posted Amazon reviews for previous books in your topic or genre. You can contact them using the same techniques mentioned above. Click on the pen name displayed with their review to reach their Amazon profile, then use the Amazon Friends invitation to send a personalized message:
Dear John Doe:
I got your name from the Amazon book review you posted of the 2003 book "Complete Guide to Organic Fruit." I recently wrote a book that appeals to the same audience, "How to Grow Organic Strawberries." If you think you might be interested in reading it and perhaps reviewing it on Amazon, I'll gladly send a complimentary copy if you'll respond with your mailing address. There is no obligation, of course.
Best Regards
These readers might not be frequent Amazon reviewers, but may consider it a treat to discover a new book in their field of interest. And there's another benefit of getting reviews from these specialized readers: Positive ratings from them can surface your book in Amazon's recommendations to buyers of similar books.
Finding volunteers to read and review your book is a long, tedious process but can be well worth the effort. If you spend two or three days inviting 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.
Remember that many folks are rightfully suspicious of e-mails that seem to promise something for nothing, and contain links to a Web site. Most users are still unfamiliar with the "Invitation to be an Amazon Friend," and often these messages are mistaken for spam, or simply deleted unread.