It’s best to pick and choose reviewers that specifically review your type of book. And, don’t send a free copy to them unless they express an interest in your book, and request a print copy or an ebook edition in a specific format. You can usually email them to ask. (Some may accept only a print copy of the book.) You’d be amazed at the high percentage of print review copies that are put up for sale by those “reviewers” on websites, and at used bookstores. And, of course, the books don’t get reviewed!
There are many wanna-be reviewers out that that are much better at collecting free books than they are at getting their reviews published. Some people claim to be reviewers but are just trying to get a free copy of your book. You should only send free books to reviewers who write regularly for one publication and only those that review books in your genre.
Reviewers posting reviews on their own small websites and in their own small newsletters should be avoided. You will likely never earn as much money on sales through those as you did on buying and shipping the book to them. It’s a better idea to offer those people a free excerpt of your book to publish in their newsletter or on their website. Be sure the excerpt contains a link at the bottom where readers can order your book!
Please also see:
Throwing Away Your Money on Review Copies?