When I first published my book (#1) in 2014 Indie reviews weren't really a thing. They may have existed but either I didn't find them or I simply don't remember them. With my second book, I definitely knew they existed but I think I only found about 5 people/sites to request reviews from. There were others but they were all pay sites. None of them decided to review my work so I had to depend solely on my readers.
Then I blinked. Two years later and I am looking for reviewers again and OMG there's a ton! I have just been going through one list (The Indie Review list) and there are 297 entries! Some of them don't count for me since they only do romance or historical or non-fiction but that still leaves a ton.
The community changed a bit. They have a lot of pull. Each site has a review policy and checklist (as required by the Indie Review List). Some have automated contact sheets and are pretty mechanical others want the personal touch. There was one site that wasn't taking reviews but they pointed out that a lot of writers are pretty rude when requesting a review, sending out impersonal request letters that didn't even have their name. They had a good point. Until I went to that site and read that I did the same thing. She suggested at least addressing the reviewer by name. A simple but very personal touch.
Now keep in mind that a lot of review sites are run but groups that don't release their names or enter a queue so you don't actually know who will read your request. Others use a contact form that is straight to the point and no frills. Still, if you are sending a request to a single person this can really change the tone of the e-mail.
Another reviewer had a neat angle. He required you send the contents of page 69 of your book. Apparently, there's a theory that this can decide whether to buy the book or give it a pass. Fortunately, my MC was doing something interesting on that page instead of brushing his teeth or taking a nap. Or researching. He does that a lot, which important for character progress but I suppose would be a somewhat lacking excerpt. Wow, I really dodged that bullet.
Another thing that is new is author interviews. I have no idea what they are but they sound interesting. Well, kinda. I have a hard time imaging people want to hear how I deal with two crazy twins every day but I suppose I could talk about my creative style... or something. Maybe my shopping habit. I did do some question and answers over on Goodreads. Maybe someone read that.
One problem I am doubtless going to run into is that this is book #3. I know that if I was a reviewer I wouldn't want to review a book in the middle of a series on its own merits. Heck, I am not sure I want them to. after I had submitted about 20 requests I realized this and I offered to send them the earlier books. Of course, considering that most of them barely have time to read the book you request I have my doubts they will want to read 2 others first. Still, with over a hundred relevant reviewers, I have hope that some of them will want to jump in.