You can use sites like Bookbub and HUGEOrange to endorse and promote your book in exchange for reviews. These sites are approved by Amazon and have literally millions of readers looking for book promotions. Readers subscribe to these sites to get free or discounted books. In exchange for the promotion, readers are asked to leave reviews. The top two sites are Bookbub and HUGEOrange.
Other sites worth checking out are:
These sites do an incredible job in boosting sales and getting reviews to roll in. The methods they use are approved by Amazon so you can promote your book free or at a discount in exchange for requesting a review. To comply with Amazon’s Terms Of Service, readers who receive books for free must state this in their review.
Please note that these websites are not free. They are included here because at some stage in your book promotion you can use these resources to boost your book exposure. More exposure means the potential to get more reviews.