Book reviews have as many styles as books do, seems like.  But as a reader, I have certain opinions about how a good review should be written.  A good review in my opinion is one that helps me decide if a book is for me and if it's worth spending part of my book budget on.

Now, don't get me wrong … I love the short ones that say, “Loved this book!  It was awesome!”  As an author, they make me feel like a million bucks.  But today I'm speaking as a reader.  And as a reader, I want to know more.

Here's a little “how-to” I came up with after reading several really helpful reviews on Amazon.  They don't have to be long, just well-considered.  If you have other tips, please feel free to add them below as a comment.

1. READ THE BOOK.  This should go without saying, but the reviewer should have read the book before leaving the review.  Now, if it sucked so bad that it was impossible to get through, that should be mentioned, and a review for that book can be done fairly.  But at least say why you didn't get past chapter whatever.  And I personally always give a book at least two chapters, sometimes three, to catch my interest, just to give it a fair chance.  Sometimes backstory is necessary, and often the first chapter or two can be slow.  Unfortunately, some people have been known to leave bad reviews for books they've never read or have even tried to read.  Some have even left bad reviews for books that are not yet even issued as ARCs (advance review copies) !!  That's just hateful behavior and has no business being a part of the reading community.  It helps no one, including the person who got a sick thrill out of doing it.  (karma, ya know?)  And a person leaving a good review for a book he or she has never read is just as bad.
2. GIVE DETAILS ABOUT YOUR IMPRESSIONS.  AVOID SPOILERS.  I want to know what you were thinking as you read the book.  Were you moved?  Angry the way things went down in the end?  Was your heart racing?  Did you have a hard time connecting with the characters?  Are they still in your head even after the story has been read and you've moved on with your life?  Tell me these things.  And if you must leave spoilers (plot details), please, leave a spoiler alert, and make it obvious.  Like this:  *** SPOILER ALERT ****.  If I think I'll buy the book, I won't read the spoilers, so I appreciate a warning.
   
3. MAKE NOTE OF THINGS YOU ESPECIALLY LOVE OR DISLIKED.  There are certain things that bug me in books.  For example, I'm not a fan of books written in first person POV, present tense (past tense, yes).  In fact, I'd go so far as to say it makes me crazy to read them and I will generally avoid them.  I really have to battle through a book written that way to finish.  That being said, I have read two books done in this style recently: Jack Sheppard's Marlowe Transmissions and Susan Ee's Angelfall, because they were such dang good stories written by great writers.  But in the review, I will mention that I am not a fan of this style, in case someone else out there is like me and wants to consider that before buying.  If you have a pet peeve that's present in the book, share it.  Personally, I don't downgrade a book's rating because the author chose this method of telling the story.  I just mention it in the review.  I will also mention humor, because I like humor in my books.  And I will mention kick-butt heroines because I'm partial to them.  I'll also talk about specific passages that highlight something I liked, like an author's almost poetic style (ex: author, Kary English, in her novella First Call).
4. MAKE IT ABOUT THE BOOK, NOT THE AUTHOR.  Before I became a writer, I never would have thought to put this on my list.  But since I recently received a pretty hateful review that seemed more about me than the books (from a complete stranger), I include it now.  Readers can get passionate about things they read.  It's a compliment to an author to know that a reader is so involved in the book and with the characters that he or she feels personally slighted when things don't go the way they think they should.  But a book review should never include anything about the author personally.  If you are one of those particularly emotional readers, write your review and then let it sit for a day or two. Go back and re-read it before you post it.  Make sure it doesn't come off as rude, mocking, or insulting.  Why?  Because even though it is your right to be rude and insult people as you please (First Amendment and all), it doesn't serve the purpose of helping other readers find good books, which is the point of a review.  And you lose credibility as a reviewer when you do something petty, aimed at the author and not the work.
5. IF IT'S A SERIES, TRY AND REVIEW EACH INSTALLMENT.  Often if there is a series of books, readers will review the first one and the last one, including information about all the books, not leaving reviews for the middle books at all.  It's more helpful to readers to see each book's merits and drawbacks individually, since they don't yet know the books.  You probably will like each book or dislike each book for different reasons.  Tell me about it.  I might buy the whole series right away based on these reviews.  I might skip it entirely if enough people say the middle of it stinks.
6. READ OTHER REVIEWS BEFORE YOU WRITE ONE.  Sometimes when I'm ready to write a review, I think I've got all the things I want to mention right on the tip of my fingers.  I type it out and think it's perfect.  Then I'll read someone else's review and I'll think, “Oh, damn!  I wanted to mention that thing too.”  It can be something you agree with or disagree with.  But you can sometimes make your review more thorough by looking at others to remind yourself about things you read.  You also can provide a counter-point raised by another reader or lend support to another reader's observation this way.
7. EXPLAIN YOUR STAR RATING.  This might seem strange, but I like it when someone explains their stars for me.  If you're a person who never gives 5-star ratings to anyone unless they write a Pulitzer Prize-winning novel, include that information about you.  It gives me a basis for comparison.  It helps me as a reader to know why you didn't give a book you really enjoyed 5 stars.  So many times I read reviews for books I'm thinking about buying and the reviewer raves about the awesome story, characters, surprises, emotions, blah, blah, blah … and then they give it 3 stars.  ??  What?  Or even 4 stars.  All I need to know is: Why it didn't earn the perfect score?  Tell me: “The pacing was a little slow,” or “I couldn't connect enough with the main character”, or whatever.  Even if it's “I never give 5 stars to anyone because no one is perfect,” that's fine.  Tell me where your head is when you assign a rating.  If you don't, I'll wonder if you left out the one bad part that would keep me from wanting to buy the book.

I'm sure there are more tips out there, probably some obvious ones I've missed.  If I think of them, I'll add them in comments below, and I invite you to do the same.

Everyone knows the review and comment system at Amazon isn't perfect.  Several authors and retailers have put up sock puppet reviews (fakes) using false accounts or by having people they know who didn't read the book or use the product put up 5-star reviews.  Shoot, you can go on that website Fiverr.com and pay someone $5 to put a 5-star review on your book.  This just emphasizes even more the need for a genuine, well-done review, written by someone who really read the book or used the product.  And if you follow the advice above, I think it will be pretty easy for anyone to tell it's the real deal.  The fake ones are usually pretty easy to spot, when you see they didn't do anything I've mentioned here.