Encourage people on your mailing list to post customer reviews on Amazon, Barnes & Noble, Goodreads, etc., if they liked your book.
A key to finding reviewers is to network. Join online groups where reviewers may mingle and gently promote your book as it nears the publication date. Join groups of authors to network with so that you can double your efforts using each other’s newsletter emails and social media. A great place to find other authors is Authors Community.
Make sure you keep records of everyone who responds positively and contact them again when your next book comes out.
Authors should keep an eye out for websites and publications that will publish reviews. Then get permission from the reviewer to reprint the review. Most are happy to do so unless they have restrictions from the original publication.
Take quotes from your book review and posts them to your website for other potential readers to see.
Familiarize yourself with the media in your surrounding area.
Choose several newspapers in your area or state.
(You can start researching here: www.newslink.org.)
Ask them if they would be interested in reviewing your book.