1. Don't Review for Review
Don't blindly do review for reviews with people you don't know as a rule, but if you do decide to do a review for a review then actually read the damn book. I decided to trade reviews with someone and he said my novel was a great collection of short stories. Clearly, it looks like someone reviewing just to get your numbers up, or even worse, one of those people who are paid the cash monies to review stuff for people. Just...don't.
2. Don't Review Based Solely on Subject Matter
Despite the fact that my book Unravelled is pretty conspicuous when it comes to the fact that it is Holocaust themed in both its cover and synopsis, one woman was taken aback by the subject matter. Upset that it tells the story of child Holocaust survivors, she rated the book two stars and admitted she had not even read the book, she was merely too sensitive for the subject matter. You know what? Not every book is for everyone. My books are not for everyone. CS Lewis isn't for everyone. Louisa May Alcott isn't for everyone. But don't give a writer a poor rating because you're not into their subject matter. If you read it and hated it for reasons other than the subject matter, then fair play and give that bad boy a singular or a double dose of stars. And also--read the synopsis first. This type of behavior can seriously hurt an indie author's sales and reviews, so think twice.
3. Don't harrass authors for free copies of their books--especially in paperback form
Seriously. I've had this happen to me and actually gave in at one point. If you're a blogger and want to review books, then sure, ask the author for a copy of the book. If the author cannot give you a free copy for whatever reason a physical form, just accept the eCopy. You have a computer, you can read it on there. Do not INSIST that an author give you a paperback book. If you are a blogger and this is your policy and writers are coming to you giving you their paperbacks, then that's one thing. But to randomly beg a stranger for a physical copy of a book is ridiculous and annoying. For some indie writers, we have to pay each time a copy is sent out and sometimes we just can't afford to spend $10-$15 for a random Internet stranger...especially when international shipping is involved.
4. Don't Buy a Book on Kindle, Read It and Return It
There's a thing called libraries where you can get books to read for free. This kind of behavior makes an author lose out on revenue and you get the book for free. When you borrow from a library, writers are compensated. When you simply steal it, it is unfair to writers...especially when you get notified of a sale only to have it taken away from you. Borrow the book from a friend, the library, whatever, but don't read it and return it. Yes, if the book is abysmal and the writing is offensively awful for one reason or another, then do refund. But don't just because you're cheap. You can also join Amazon Prime and borrow the books for free, which the author DOES get compensated for.