as much as I love recieving, there is nothing I love more than posting a review. I am so full of myself I'm dazed for a couple of days after leaving a particularly good review. (Sheesh, I'm so preachy!)
The elements of a good review: 1) NEVER say: "I know what's going to happen to so and so, you're going to do such and such, aren't you?" This is the worst review, aside from a flame that one person can give to an author. Muses get chased away by good guessers. So even if you know where the story is headed, DON'T SAY IT.
2) DON'T tell the author what to do with their story, even if they ask. If you can't hold back, email them, don't tell them in a review. "Oh, please let the mother live!" when obviously, she's doomed.
3) Always describe how the work made you FEEL, even if it was negative. An author might have been going for that feeling, and to hold back here is death to the story. For example, a certain passage grossed you out, so just say so, then bring up another example of how the author evoked another feeling from you. Authors are trying their best to connect to their readers, not just trying to connect to themselves. If no one is telling that author how that story made them feel, then they might think that the story isn't worth telling.
4) Hey, poster below me, what's another element of a good review?