Speaking about what you are up against....
Regardless of the genre, review websites and review bloggers receive anywhere from 10 to 50 review requests per DAY. Some suffer a lot more. They are swamped, backlogged and buried in requests. I had one review source contact me who said, "Chris, there are 34 ahead of you, do you still want to proceed?" I answered in the affirmative, but realized this was not a guarantee of a review, but only a perusal of my query, and then, and only then, would a decision be made. What has changed to make it doubly hard today is that about 75% of the reviewers are allowing self-published authors to submit. This is all fine and well, but it adds to the traffic jam. Only some years ago, indie authors were refused reviews--now they are becoming commonplace.
I've harped on this before--there is a serious industry glut. There are far more submissions to agents and publishers than ever before. Take in the fact that sales are down all across the board, and what you have is a cautious industry that is making mergers, cutting back on staff, eliminating entire categories (like YA), and accepting less debut authors. This trickles down and forces authors to promote and market their back-list titles and this usually means hunting down reviews.
You are aware that Amazon's fairly recent policy has really slaughtered the amount of reviews you are seeing today. They require a $50 minimum purchase within a year, an account and a current credit card to post a review. If this doesn't smack of 'product lock-in', I don't know what does. People have enough expenses as it is, let alone open an Amazon account and spend money there. They also have a stipulation that friends, family and relatives will be excluded from reviewing books. I ask you, is not my family, relatives, fans and friends who buy my books? Amazon's excuse for this was that they had to weed out fraudulent reviewers. Ooooooooookay.
Now that you know what you're up against, let's damn the torpedoes and hit flank speed. Google "review sites for your genre or category." Something to that effect. If you get the best 10, 50, or 100 list, click on each website or blog site starting from the top on down. Make sure the sites are current and active. You might get error messages, parked sites, 401s, or is it 404s? Read their policy and guidelines carefully and make notes on exactly what to include in the submission and how it is to be sent. If you skimp on this or get it wrong, kiss that request good bye. They can't tolerate any deviations from their guidelines.
So help me, you had better personalize it and talk it up a bit before you get to the bones of your submission. These review people want to feel human contact and not some spam onslaught from a robot. Read their bios, comment on their bios. Add a few lines about their favorite sub-genre, pets, family, education, reading habits. Use their real name. If you can't find their name anywhere on the site, use a general greeting but continue with the comments. I usually apologize for not noting their name if I can't find it. You can go to their FB or Twitter page and sometimes find it there. Check out Goodreads, and if you are a member at GR, by all means put your book up for review there.
If you are trade published, ask your publishers which review source they automatically send to--you do not want to cross-post with your publisher, hitting the same review source twice. That can get you yanked out of the review list. Make a note of what format is expected. It could be the more popular PDF, or it could be an EPUB format that the reviewer finds easiest to read on their device.
Start your review campaign at least three months in advance of your release. Some reviewers will take ARC (author review copies) well in advance of publication!
They will try to get their review to coincide with the release of the book. Other reviewers don't want a gun to their head, expecting to rush a review for anybody. Again, read the policy. The reason you generally want to submit early is that it can take so long for a review to materialize. It could be a few months or longer. This is a maddening process akin to submissions to publishers and agents. In fact, it is not much different. You'll find one reviewer who wants a short intro query via regular email. They want to feel you out. Don't--don't attach your book or anything else. Other reviewers will instruct you to fill out their long forms and upload material there. Obey the rules or suffer the consequences.
They will contact you if you will get a review. Many of them will post that review on Amazon and many of the other retail stores online. That's a great perk. You should also use that review by spreading it around to your social media sites and other sources. Bring it to your publisher's attention.
How many review sources are enough for good saturation? Answer: as many open and legit review sources as you can find. The odds are against you. You might get one review for every 15 submissions. If you personally know the reviewer you've just upped your chances significantly. Below is my list. Since the genre was romance, more precisely romantic suspense with some erotica, I found these review sites and gave it a go:
REVIEW REQUEST SENT TO AAR ROMANCE (DABNEY) 1-17-2019
REVIEW REQUEST SENT TO AESTAS0 ROMANCE BOOK BLOG: 1-17-2019
NATASHA IS A BOOK JUNKIE—1-17-2019
RED HOT BOOKS—1-17-2019
JOYFULLY JAY, ROMANCE REVIEWS—1-17-2019
DIRTY GIRL ROMANCE—1-17-2019
COFFEE TIMES ROMANCE—1-17-2019
TRUE STORY BOOK BLOG—1-17-2019
ROMANCE BETWEEN THE SHEETS—QUERY ONLY—1-17-2019
ROMANCE FOR THE BEACH—QUERY ONLY FOR PDF—1-17-2019
THE ROMANCE DISH—QUERY ONLY—1-17-2019
TBR—TO BE READ PILE—SMALL FORM, QUERY ONLY—1-17-2019
YEARWOOD LA NOVELA—QUERY ONLY—1-17-2019
JOYFULLY REIVEWED (JOY AND MELISA) QUERY ONLY—1-17-2019
TYPICAL DISTRACTIONS ROMANCE—QUERY ONLY—1-18-2019
NON DE PLUME ROMANCE—FORM SENT—1-18-2019
NOT ANOTHER ROMANCE BLOG—FORM—SENT—1-18-2019
ONCE UP AN ALPHA REVIEWS—SMALL FORM-EMAIL—1-18-2019
FOR THE LOVE OF ROMANCE—QUERY WITH SYNOPSIS—1-18-2019
ADDICTED TO ROMANCE—RENNE, QUERY ONLY—1-19-2019
WANTON READS ROMANCE—EXTREMELY LONG FORM—1-19-2019
UNDER THE PAGES ROMANCE—SHORT FORM AND LINK—1-10-2019
ALICEVL.COM ROMANCE—SHORT QUERY—1-19-2019
MY LOVE OF ROMANCE, RENNE—EMAIL QUERY—1-20-2019
DAILY BOOK REIVEWS—SHORT QUERY ONLY—1-20-2019
FOREVER YOURS ROMANCE—LONG SUB-ATTACH—1-20-2019
ALL ABOUT ROMANCE—QUERY ONLY—1-20-2019
BLACK RAVEN’S REVIEWS—LONG FORM—1-21-2019
BOOK LOVER INC REIVEWS—LONG FORM—1-21-2019
DARK DIVA REVIEWS—LONG FORM—1-21-2019
NAUGHTY EDITIONS REVIEWS—QUERY—1-21-2019
RITES OF ROMANCE—QUERY, BOOK,--1-21-2019
LONG AND SHORT ROMANCE REVIEWS—SHORT FORM—1-21-2019
MANIC READERS—LONG FORM, MULTIPLE CHOICE—1-21-2019
THOUGHTS BY TASH REVIEWS—SHORT FORM—1-21-2019
BEAS BOOK NOOK—EMAIL SHORT FORM—1-21-2019
BOOKS MAKE ME HAPPY—SHORT QUERY—1-21-2019
BOOK PUSHERS—SHORT QUERY FORM—1-21-2019
BOOK SMUGGLERS, ANA AND THEA, EMAIL QUERY—1-21-2019
CARABBEAN ACCENT BOOK REVIES—COMMENT QUERY—1-21-2019
CONFESSIONS OF AN UNSUSPECTED BOOK WORM-QUERY—1-21-2019
DEAR RESTLESS READER—LONG EMAIL QUERY==1-21-2019
FORGET HOUSEWORK I’M READING—LONG EMAIL—1-21-2019
LAURA’S REVIEW BOOKSHELF—INITIAL QUERY—1-21-2019
MALDIVIANS PASSION FORM ROMANCE—QUERY—1-21-2019
MARYSE’S BOOK REVIEWS—QUERY/SUBMISSION—1-21-2019
MY TANGLED SKEINS REVIEWS—QUERY SUB—1-21-2019
BAD BIRD READS—EMAIL, SYNOP, SAMPLE, LINKS—1-22-2019
ROMANCE NOVELS FOR FEMINISTS—BOOK SUB, QUERY-1-22-2019
SHAMELESS BOOK CLUB (SMUT)—FULL—QUERY—1-22-2019
THE BOOK TART—SMALL EMAIL FORM—1-22-2019
THE ROMANCE REVIEWS-MEMBERSHIP—LARGE DATA FORM-1-22-2019
THE ROMANCE STUDIO—LONG FORM, FULL, 1-22-2019
WHAT I’M READING-IN SEARCH OF ROMANCE—QUERY—1-22-2019
LOVE IN THE MARGINS—LARGE FORM—1-22-2019
Sorry, no clickables here. Didn't have the time.
Why so many? Because I was a slimy little smelt in the middle of the Pacific Ocean. It took me four days, eight hours a day to make all of these submissions. Prepare for the time and workload knowingly.
Red-shifting otta here....