I'm doing a writing circle with friends where I had to review a fan fiction. I was far from the ideal reviewer for it because I didn't play the game it was based on, only a few hours of a later one in the series. Plus, I've barely read any fan fiction before.
I left a lot of comments for the author (more than my co-reviewers). Some of what I said likely stemmed from my ignorance of the source material and may not have been helpful, since I expect much of the appeal of fan fiction is for fans to see familiar characters in a new adventure (or maybe the reverse, new characters in a familiar setting). I had no idea who any of the characters were, nor much about the setting.
But other comments I made I think were genuinely helpful. "Show not tell", for example, is fairly universal. I also like to think that I'm pretty good with grammar.
As a reviewer, how can I minimize ignorant, unhelpful comments about a fan fiction while maximizing helpful feedback?