Book Reviews have lots of guidelines around them, when connected to official retailers and reader sites. You should read all their guidelines or face getting into hot water.
Amazon & Goodreads Review Guidelines
Amazon: https://www.amazon.com/gp/community-help/customer-review-guidelines-faqs-from-authors (Read No.2 in particular!)
Goodreads Review Guidelines: https://www.goodreads.com/review/guidelines AND
Author Guidelines: https://www.goodreads.com/author/guidelines
By contrast, an endorsement (a positive, named review) is more personally done, usually by email or post, before the book is out. These can be printed inside the book (after title page), 1 or 2 on the back cover, or indeed lifted into the “endorsements” section available on Amazon Author Central (once book is officially ‘published’).
About Doing Book Raffles
(Plus Selling your Book I.P. and Branding a Book Series)
These sites help you send out advance reader copies or give away reader ‘chapter 1s’ or run book competitions.
Book Funnel giveaways (highly recommended)
With BookFunnel features, you can make a landing page to giveaway a chapter of your book or early review copy. The mid-list author package is best ($100 p.a.), because you can also collect those email addresses. If however, you think those people will not want to hear from you, select the first-time author package, for $10 p.a. (ARC=Advance Reader Copy)
Gleam sweepstakes/giveaways (via social media)