I have been thinking about this ever since I saw the question posted, and regret that I am only now getting my thoughts down on metaphorical paper. Asking for advice on writing fanfic is like asking for advice on how to build a spaceworthy vehicle from scratch. I gave up trying to get every piece of advice I have in one place because I found most of it on the sites of writers who put it better and more succinctly than I ever could.
You can’t do the writing if you haven’t done the reading. No one is going to hand you a textbook on the subject like your math teachers did because no comprehensive source exists. Fortunately there are many, many sites out there on how to write fanfic and how *not* to write fanfic. Start by plugging
how to write good fanfic or
fanfic fan fiction resources into your search engine of choice. Read the pages that look most promising. Bookmark particularly helpful pages and take notes. Most pages will have links; follow any that look relative or interesting. Snake your way through the subject. This is a good time to surf until you drop. You’ll see a lot of advice repeated. (You’ll also hone your search engine skills.) This is to your advantage because it is more likely to sink into your and stay there for later use.
Once you’ve identified particular aspects of writing that you want to pursue, incorporate those key words into your searches, such as
fanfic characterization or
writing POV.
Particular names that stick out in my memory of how-to writers are Merlin Missy, DangerMom, Helena Handbasket, and Minotaur.
Fanfic has its own particular pitfalls, but it does fall under the heading of fiction. Many books have been published on how to write fiction. Hit the nearest library or bookstore and go browse. This may seem like overkill, but developing good writing skills is work, and you have to put in the effort if you hope to get anywhere.
Read as well as write. You’ll soon be using what you’ve read to pick apart story elements and learn from others’ mistakes. Don’t limit yourself to Trek or Klinfic. You may not know the specifics of whatever fandoms you end up reading, but you are looking for examples of techniques both good and bad, not just a good story. Each fandom has its own quirks, conventions, and standards. Klinfic is particularly problematic, largely because it is overflowing with cliches and S(t)u(e)s. After reading a particularly putrid piece of prose last winter, I snapped. Since I couldn’t break the author’s knuckles, I took out my frustrations in a rant entitled something like “Things I Never Want to See in Klinfic Ever Again, Ever”. Once I’ve taken care of some other Forum matters, I’ll hunt it down, clean it up for public consumption, and post it to this thread.
Caveat #1: There is no fandom, anywhere, that does not contain some slashfic. The best writers, the ones you want to learn from, are also amongst the most versatile. They have probably at least tried their hands at slash. Most but not all slash is labeled as such in the header.
Caveat #2: One reader’s squick is another’s idea of prime entertainment. The author may not have thought to include a warning about a particular theme or event because to them* it wasn’t an issue. You never know when you’ll be happily reading along only to run face first into your own personal gross-out nightmare fuel. It’s a rare event, but it happens. To those who've been traumatized by a squickfic, all I can say is that I’ve been there and I sympathize.
Qunchuy is right: you need an editor, usually referred to in fanfic as beta readers.
Siubhan and Joan the English Chick explain why. Prize-winning professional authors use editors, too, although they are paid for their work while betas are not. }}: /
Spelling counts. My word processing and email applications have spell-checkers. My browser has a spell-checker. The text-entry field box thingy on these Forums has a spell-checker. They are becoming hard to avoid. There is no excuse for not spell-checking your opus-to-be. If you’re too lazy to do so, you are too lazy to develop the skills necessary for writing passable fanfic.
Grammar counts. Getting grammar right is more difficult because there are different and conflicting standards of English sentence construction in use. If possible, have someone else give your story a once-over before surrendering it to your beta. They* are likely to catch things that you missed. Also investigate Strunk’s "The Elements of Style". It is an excellent resource on basic composition and is
posted online in its entirety.
Random yet useful rule of writing imparted to me by Alan Dean Foster: you are only allowed one convenient miracle per story.
My corollary: Once you’ve used that up, you have to do it the hard way with clever plot construction and foreshadowing.
So there’s some advice to get you started. I hope you will follow up on at least some of them. If you’re still interested, we can try to talk specifics.
*Yes, I know using “they” to replace “he or she” creates a situation in which subject and verb do not agree. Unless and until a writing contract hinges upon it, I will continue to do so, and every teacher who ever docked me points for it can *%^@!!$*+ my å∆∞$#*&∆˚ßI>* until their √∂˚$^{{∆µ#?∂&~ fall off.