* A good review will "ignore" genre for the actual writing.
When you review, critique the writing itself, not the genre or your love or hate of that genre. Not all drama is good, not all fantasy is bad. It's the writing itself that makes it good or bad and that is what you need to focus on. If you can't set aside you personal feelings for the genre, then you should decline to review the piece.

* A good review is detailed.
A good review will be clear in each point it makes: where the critique refers to in the writing is quoted and comments are clear and specific. The best review will also help an author who may be stuck by asking questions that will make the author think about his/her writing. Only if questions don't help or the author asks for suggestions should you offer specific suggestions, and then you should make at least 2 or 3 for the author to consider. Try to keep your suggestions from sounding like you're trying to rewrite the author's story for him or her (using "I would write it like this..." is one way to avoid this problem).

* A good review is organized.
The best critiques start at the beginning of the writing and work their way through. You don't read the piece all mixed up, why should the author have to search through the pages of his or her writing to see what you are talking about in the various points of your review.

* A good review is tactful.
Pointing out problems in someone's writing can be done in a diplomatic manner without compromising the issue being brought up. Try using language that doesn't accuse or point fingures by saying "I think" or "I feel". If something is more of a style issue, admit that you realize it might be a matter of style. You can be honest in your opinions without sounding like you're attacking the author.

* A good review is positive.
While it is true that the problems in a piece need to be pointed out so we all can be better writers, there are positive ways to express negative ideas. "This seems more like a list, are you sure that's the idea you wanted to convey?" "I might be able to get into this better if there was more description." "What is she thinking right now? How does this smell?" One way to make a critical comment seem more positive is to frame it in "I" language: I don't understand, This confuses me, I can't see, If it were me I'd try to. "I" language is less negative and tends to not be seen as an attack. Positive reviews also point out what is GOOD in a piece. Does a description strike you as particularly vivid? Was something well phrased? By pointing out the good things, you encourage the author and help him or her see what works and what doesn't.

* A good review pays attention to concerns of the author.
If the author needs to add length or cut things out of the piece being critiqued, the reviewer will point out places where the author may be able to accomplish his or her goal. If the author is concerned about how well they describe things, the reviewer will comment on this particular facet of the piece, offering suggestions where necessary. Sometimes we don't know what an author is concerned about, but if we notice a pattern of weakness in a particular area (descriptions or background for example), we can use that pattern to help guide our critiques as well.

* A good review gives an overall opinion.
Did you like what you just read? Did you dislike it? Either way, you need to let the author know about how you felt about what you read. What features of the writing did you like in particular? The descriptions? The characterizations? Were you on the edge of your seat or drawn into the story despite yourself?

* A good review will note where it agrees or disagrees with a previous critique.
Each of us has a unique perspective. Even when we agree with another person's viewpoint, we can agree for different reason than what the other believes. By pointing out where you agree and disagree with a previous review, and WHY you agree or disagree, you give the author more to think about as they edit the piece. You may also help the author come to a decision when s/he may not be so sure that the first reviewer is right. If you confirm to an author that his descriptions could be improved upon, as noted by another reviewer, then the author may end up taking a solid look at his descriptions, even if he initially felt that his descriptions were okay.

* A good review will always end with a positive note.
Writers are like anyone else, bash on their work enough and they get discouraged. And writing is like anything else in that no piece is entirely good or bad. You can find something good in every piece if you try, even if it is as simple as "It was informative". This may not have been what the author was aiming for, but it is still a positive quality. Look for something good and make sure to end on a positive note.