Wanna know why I'm such a bitchy beta and always go on about the same old cliches and mistakes? It's because when I came into online slash fandom in the second half of the Nineties, these were the resources I was pointed towards. Yep, it's time for a list of comprehensive, intellectual fanfic guides that discuss the dos and donts of fanfic writing. I don't agree with absolutely everything on every site, of course (oh, man, how RPS was hated on in pre-hobbitslash days), but if you really care about the craft of writing and specifically fanfic writing, check these places out. They're even more valuable these days because the arts of beta reading and constructive criticism aren't appreciated any more and you just get flamed to hell and back for pointing out a typo. So I'll just link to these pages to show I'm not conversing out of my rectum whenever I tell people not to use "the other man", ask them to show rather than tell, et cetera. My writing isn't perfect, hell, nobody's is, but these tips can help you become a better writer (and a more educated, critical reader). So, yeah. Go read.
Citizens Against Bad Slash *excellent* site. Snarkery to the max. The Writing and Rants sections are of the good.
Ten Little Peeves. The examples on this page, especially the anti-epithet B7 one, made me spit cola.
Ms. Nitpicker: How To Write Marginally Readable Fanfiction. How to Write Better Fan Fiction . Geared towards longer stories, and I don't agree with some of the techniques mentioned on here, but there are a few great tips, especially for plotty and actiony stories. Some of this stuff is absolutely golden.
Bad Fanfic! No Biscuit! Ahhh, I remember this site way back from the Sith Academy days. Good writing is always relevant. And some of the intentional badfics are lolarious--and educational!
Minotaur is sadly no longer with us, but his invaluable guide,
Minotaur's Sex Tips for Slash Writers, lives on. Sllash tips from a gay man's perspective, yo. (Of course, each gay man is different, so everyone would give you different advice, but this site is great for the basics.) Rereading this site, I'm realising just how often I think of phrases and concepts I first picked up from here as a fledgling slasher, and how they really have stuck as great rules of thumb. Also comes with NSFW illustrations.
Dr Merlin's Guide to Fanfiction. Another oldie'n'goodie.
This is not a writer's guide, but I'll include it anyway:
The Generic Slash Defense Form Letter. For whenever someone whines at you for being an evil slasher. It's a short collection of very intelligent and very articulate comments from slash fans from way back when. Surprise surprise, it's from a Blake's 7 mailing list. Just seeing the amount of brains in these comments is enough to give me a nerd boner. See what I mean about B7 slash fandom being hardcore, kids?
Aaand there's this one site that I think may have been lost forever (I can't even remember its name, so I can't even use the Wayback Machine to find it). I used hilarious X-Files examples to illustrate How Not To Write. Anyone remember what that was called? I seriously last remember looking at it in 1999, so it's probably dead and gone?
Anyway. Hope these links come in handy. If you've got other good sites to recommend, gimme!