Even if you self-publish, you will spend months of preparation for a release day that may go out with a whimper, not a bang. In some respects, a lack of reviews is worse if you have self-published, because those who follow that route have to do all their own marketing and promotion, a task which requires direct involvement with readers.
Why are reviews important?
Like any other product on the market, people rely on the recommendation of others when they choose a book to read. In traditional publishing, endorsements by well-known authors and public figures are a key element in marketing. In the self-publishing world, success rests on the number of readers on Goodreads, on Amazon, and on blogs who will give your book a 5-star review. Without this kind of public endorsement, it may be nearly impossible to promote your book, especially if you have enrolled in KDP Select.
Amazon KDP Select giveaways are still the reigning book promotion tool. There are dozens of sites that will post your free days, but nearly all of them require a minimum number of reviews. It's one of those chicken-and-egg dilemmas. You can't promote your book without reviews, but you can't get reviews without promotion.
Should you pay for reviews?
If you are a new self-published author, don't pay for reviews.
Traditional publishers have long-standing ties with the media which self-publishers don't. This often drives self-publishers to pay for publicity. In my experience, paid reviews don't have nearly the clout of regular reviews posted on Amazon or Goodreads. For one thing, they have limited shelf life. A paid review may get posted on Blogcritics and then picked up briefly by small publications, or it may simply get sent to you for your own use. Very rarely do these reviews make it into larger media outlets, where they will reach the maximum number of people. Of course, you can always shell out $400 for a Kirkus review, but you take your chances. A good review in Kirkus is like an endorsement from God, but a bad review is the kiss of death.
How to get free reviews
Fortunately, there are mechanisms in place for getting reviews without spending a great deal of money. Giving away copies en masse is one route, targeting individual reviewers is another.
Librarything allows authors to give away copies of their books to Librarything members. (Read their policies.) Authors of self-published ebooks can give away up to 100 copies. Reviews are not required of readers, although they are recommended, so don't expect more than a 10% return rate. But even 10 reviews will enable you to post your free days on some of the larger freebie sites if you have enrolled in Amazon KDP Select.
Bookblogs is a great site for finding reviewers and for posting your giveaways. Explore the "groups" section and join the groups that are relevant to your genre. When you give away a book, or are looking for reviews, you can post it on the group site. You also have the option of sending a message to every member of that group.
This is a great resource for book review blogs. It's an alphabetical listing of individual bloggers as well as book reviewer lists. This is your one-stop shopping guide to reviewers.
Book Blogger Directory
Over a thousand book blogs, very nicely organized by subject, and alphabetically.
Best of the Web
Best of the Web book blogs organized alphabetically. Not as easy to navigate as the book blogger directory.