Book reviews on Amazon help your book get higher rankings and more sales. Don't be afraid to ask people to review your book. Send out e-mails or ask on social media. Include a link to make it easy for them to click and write a quick review. You can also ask Amazon's top reviewers to review your book. You may need to send free copies to people you are asking.
Here is an article called, "Why Book Reviews are Important on Amazon," with eight reasons your book should have at least 10 reviews.
Patty Pacelli, author, editor and publisher, writes hints and tips for authors and writers about self-publishing, writing and marketing your book.