Critiquing is a part of learning to write well because it exposes you to techniques you may not have thought of or experienced. That said, here are suggestions on how to critique the work of others. Experiment with these, then develop a style that fits you.
REVIEW ETIQUETTE: The purpose of a critique is to help the writer improve his or her writing, not to slam the work. Destructive criticism or the deliberate trashing others' work, no matter how bad a piece is, has no place in a workshop. Likewise, since it's presumed that anyone presenting work for critique is here to learn how to make it better, a whitewash job of reviewing doesn’t help the writer. Be honest, but be courteous and positive and respect the writer's efforts.
WHAT'S EXPECTED IN A REVIEW: Learning to review well is not something that comes easily to every writer. It can take years to master, but along the way, you will find yourself learning as well. To that end, let’s approach reviewing and critiquing in two stages: one for beginners, one for more experienced folks.
FOR EVERYONE: At a bare minimum, a review should express what you thought of the piece. A review needs to be more than one word or one or two sentences saying "Good" or "I really enjoyed this story" or "I think this is good, but I think it needs to be longer." These are not acceptable reviews. As a general guide, a review should probably be at least 100 words. There's no maximum length, and I’ve seen some reviews that are actually longer than the piece being reviewed.
Use the four principles of critiquing. If you're new to critiquing, start small and keep your reviews short but as informative as possible.
1. Begin with something positive and encouraging.
2. What do you feel is working and what is strong in the piece?
3. What needs work and what parts are weak?
4. Offer suggestions for improvement if you are comfortable doing so. Otherwise, wait until you have more reviewing experience.
5. Always respect the writer’s voice and style. Never attempt to rewrite the piece according to your style or personal preferences.
FOR BEGINNERS: Focus on why you liked or didn't like the piece in terms of what worked or didn't work for you. If you think the story needs nothing more, say so, but don't stop with that. Here are three things you can focus on.
1. Did you like the piece? If so, what about it impressed you? If not, what do you think was missing or what detracted from your enjoyment? Did the opening grab your attention and did the piece hold your attention throughout? How did the piece make you feel? Does the ending work (assuming it's a complete story)? If the ending does not work for you, what do you think would make it better?
2. How is the overall writing? Is it smooth, or is it rough and in need of work? Does the story flow smoothly? If there are problems, try to give the author some idea of what you think might help.
3. What did you think of the characters and the narrator (the one telling the story)? Are they well drawn and believable?
FOR ADVANCED REVIEWERS:
All of the points mentioned for beginners apply, but you may wish to delve more deeply into the piece. Here's a more detailed list of areas to consider. The review doesn't need to cover all or even half of these. What you choose to point out is at your discretion.
1. How did the piece make you feel?
2. Did the opening hook and engage you immediately, or was it a slow beginning? Did the story begin in the right place, or should it have started sooner or later in the chain of events?
3. Did the piece flow well from point to point?
4. Were there areas of confusion?
5. Were there any places where you wanted to stop reading?
6. Did the characters resonate with you? Were their personalities (and names) appropriate for the piece? Were the characters believable in the story's setting?
7. Did anything feel out of place or incongruous to the story?
8. Did the writer engage all the senses (sight, smell, hearing, taste, touch) when appropriate?
9. Did you feel as if the writer was telling you the story, or were you experiencing (being shown) through the characters' perspectives?
10. Did it engage you emotionally? Did you laugh, cry, feel anxious for the characters, etc.?
11. Was the level of conflict (physical and emotional) appropriate for the piece?
12. Was the writing itself smooth throughout? Are there specific issues with grammar or punctuation that you want to point out? You should avoid nitpicking a piece to death, however. Remember that your purpose is to critique the piece, not edit it.
13. Was the tone (language and word choices) appropriate? For example, if the story is not set in the modern day, did the writer use words or expressions (or even character names) that felt out of place for the setting?
14. Did the story end in a way consistent with how it was set up in the beginning and written throughout, or did the ending feel forced?
15. What impressed you about this story?
From time to time, you may encounter a piece that requires significant rework in many areas. Instead of attempting to cover everything—which might discourage the author—point out a few of the major things to work on and save the smaller stuff for later when the piece is coming together better. If the writer makes significant changes, some or all of those small things may be taken care of in the process.
Finally, some authors may bring polished stories to ensure that they've caught everything, and they well may have. Your job as a reviewer is to evaluate whether a piece works as is and is publication worthy. Don't assume the piece has problems, and don’t offer changes simply because you think you’re expected to find something wrong with it.