I've been reading Fan Fiction for a while now, and I've come to a conclusion: there are three kinds of HP Fan fiction, the fan fiction where the author writes like 3 words and then abandons the story. The other kind has so many cliché's in it that I read one chapter, or if I can stomach it, get all the way to the end, the surprise twist is that Snape or Malfoy is Harry's boyfriend. The last kind, a minority, is the good kind, usually written by an established author, that can never be updated soon enough. this is about 2-3 % of HP stories.
Another thing i cant stand about some stories, is that they give no warning when there's gonna be some guy on guy action. I'll come to a good story, and then all of a sudden, bam! Gay sex or yaoi or whatever you wanna call it. Give me some warning.
Some stories, the summary just seems too good to be true, so I check the authors notes and the beginning and end. Just now, i was about to read a story, but checked the AN, and the author was running a polls, in the reviews, about what should happen, which is something I can't stand. I want those 10 seconds of my life back. Doing polls like that only proves that you have no imagination.
Another thing I can't stand, those little copy and paste things people always put in their profiles. Oh, if Abercrombie and Fitch said it was uncool to breath, 92% of all teenagers would be dead, or some stupid thing like that, or 98% of teenagers have either smoked, drank, or tried drugs, C&P if you haven't!! It is really annoying. I like how the last one calls over 1 billion people druggies. In fact, I hate chain messages and letters so much, whenever I get junk mail, I mail the sender a sock or something, or my dirty underwear.
My guidelines for HP fanfiction are these:
#1 Never post an abandoned fic. If you're going to abandon a fic, just delete the story, and set up a plot bunny file or something like that, and put the story in there.
#2 Never have polls where readers can vote to see which way the story is going to go.
#3 If you're going to write yaoi, please put that in the description. I, for one, do not enjoy guy on guy action.
#4 Only do clichés for fun. some clichés, its done in an intentional way, to be funny, others, its weird or annoying.
#6 Don't put your fantasies on the characters. If you want to give Harry or some other male a harem, you'll probably lose a lot of girl readers. In adult fanfics, authors put their fantasies on the characters, ie, the main male character will have a huge dick, or somebody attractive will be sex hungry, etc.
#7 Spell check. its pretty easy, and if you don't know how to spell you shouldn't be on fanfiction.
#8 Make bashing fics make sense. If you're going to make a manipulative Dumbledore fic, make an argument for it. Say Dumbledore bound Harrys magic or something like that. Why would he do that? What purpose would it be for? How would it benefit him?
#9 Make sure people can tell where the story begins, or ends, and where the authors notes start.
#10 Never reply to reviews in the authors notes. I see this sometimes, its where a reviewer asks a question or gives advice, or something like that, and instead of just hitting the reply URL in the email fanfic sends you, they decide to reply IN the chapter.
#11 Proofread. Some stories, a chapter, or even the entire story is in bold for some reason, or underlined, or in italics.