1) Your focus should be on the writing itself, not on whether you approve or disapprove of the subject matter. If reading something makes us really uncomfortable, it's okay to express that discomfort, so long as we don't turn our subjective reaction into a judgment. Often discomfort comes from confusion or ignorance, so a call for more explanation or clarity may be appropriate.
1a) In a class like this, where students are invited to write about intensely personal and perhaps difficult subject matter, it's important that everyone feel safe. Comments such as "I disapprove of your lifestyle," "You [or your father/ friend/ brother/ mother/ sister/ spouse] must have been crazy to do that," "I think your decision was immoral," not only threaten everyone's sense of safety, they aren't helpful to the writer either.
I know it's difficult to separate personal feelings from critical judgment of a piece of writing, but as members of this workshop, we have to try.
2) The writer needs to know where her/his writing is strong, clear and effective. Is there sufficient detail? Are the verbs strong and active? Are there wordy places that could be condensed or cut?
The writer needs to know if the reader could follow the narrative easily, or if there were points of confusion. The writer needs to know if the ending felt satisfying (which is not the same thing, necessarily, as the reader "liking" the ending -- but that it resolved issues (again, not necessarily happily) that were raised in the narrative. The narrative should end without leaving the reader with a lot of unanswered questions.
3) There is a difference between a journal/diary entry and a personal narrative, even when they both treat the same subject matter. The diary entry is meant for the writer; style and clarity aren't considerations unless the writer makes them so. But these narratives are meant to communicate thoughts and feelings to someone else, and do so in a way that engages the reader. As readers we would rather have one scene in which we "see" the conflict between the narrator and her bullying older brother (what does he say? what does he do?) than be told 10 times that "my brother is a terrible bully. he's really mean." As helpful critics, we can point out scenes where we can "see' what the writer is describing, and places where we are just told about it.
4) Although a personal narrative has fewer formal constraints than a traditional essay -- it needn't have a thesis statement, for example -- it does need to have a point, and when we've finished reading the narrative we should feel we've "gotten somewhere." For this paper you were advised to choose an important event -- a decision point, a high point, a low point -- or something else specific and self-contained. So when you are working on your critiques, ask yourself: "is there a point to this? What is the writer trying to get across (and is s/he succeeding)?" If after a careful reading you have no idea what the point is, the writing probably lacks focus and clarity.
A good narrative builds toward something. If the moment of strongest emotion occurs on page 2, and there are 5 more pages, the reader keeps waiting for something more to happen, and is disappointed when it doesn't. If all of the scenes or events have the same level of emotion, the paper will be "flat." So another question to ask yourself is "does my interest build as i read? or does it slack off?" If it starts to slack off, can you identify where that happens?
5) When you offer your suggestions, remember that these are suggestions for improving the narrative, not for fixing what you may perceive to be a problem in the writer's life!