I've heard "I don't know how to write a review" many times now as I've talked to friends who read Jasmine: Energy Book 1 and told me how much they enjoyed the story. After reading reviews in the New York Times or other large outlets, I see how writing something thought provoking and compelling while remaining in impeccable prose is daunting.
The reality is writing a review can be a very simple process and it benefits the authors greatly if you follow these steps.
By no means do you have to follow this exactly. It is your review so use your own creativity. However, as a writer, these steps can help me grow and this kind of feedback is invaluable!
Step 1: If you are reviewing on a book purchasing outlet like Amazon.com, Barnesandnoble.com, Smashwords.com or any place there is a summary of the book already, move on to step 2. If you are posting to your blog or other outlet, you can create your own synopsis of the storyline or coy and paste what the publisher put on Amazon.com. After writing reviews for many years, I find copying what is there saves me time and I avoid re-inventing the wheel.
Step 2: What did you like about the book? Were the characters well developed? Did you like the message? Try to write 3-4 sentences about what worked in the book.
Step 3: What didn't you like about the book? Was the protagonist (bad guy) unbelievable? Did the world the author created fall flat? Point out things you think could have been better. Use as many or as few sentences needed to point out things that bothered you.
Step 4: Who do you think would enjoy the book? Maybe it's not your cup of tea but would an anime fan take much more away from the book? Maybe you loved it and everyone who loves a good romance would enjoy it with you. Use as many sentences as needed to point out who would enjoy the book.
Step 5 (Optional): A lot of readers like to know if there are a lot of swears, steamy sex scenes, excessive violence or gore before buying a book. I try give readers a heads up while writing reviews.
If you absolutely hated a book, it's OK to say that as long as you say why. Don't attack the intelligence of the author in a review or his/her questionable lineage. Sometimes, it's best to not write anything at all and that is your choice.
However, if you enjoyed your read, (even if it wasn't a block-buster story) let the author know by writing a review.