(from sartorias Who got it from burger_eater)
All things I have found useful in the writing of works in my genre. (Epic fantasy, if you haven't guessed by now. 0:)
1. Read fiction -- in your genre and out of it. This will introduce you to new words, new tricks, new stories, and new styles -- all in their native habitat.
2. Read history. Particularly, read primary source, from all over the place and all sorts of eras. This is not research, though tidbits may prove useful in the future. This is to knock your block off. To open your mind to the possibilities. To expose you to people who think very, very, very differently from you. This is to both keep you from reaching for things the way you experience as the default and prevent your trying to use only your imagination to construct how a different society would treat things.
3. Read myths, legends, fairy tales, and folklore. This is also to open your mind to the possibilities. Plus it's a lot of wonderful public domain stuff you can pilfer. How many variants of Cinderella do you know? There are hundreds. Do not assume you know European folklore -- there are 200 Grimms' Fairy Tales and only a handful are well known. Joseph Jacobs's collections of English fairy tales (here and here) and Celtic fairy tales (here and here) -- well, you probably know Jack and the Beanstalk and may know a few others but I wouldn't bet on it.
4. Read how-to-write books, but bring along a salt-shaker. You can pilfer techniques from them, but what works for the author may not work for you. Test and experiment before you wed yourself to one.
5. Make your ideas jump through hoops. You don't have write them as they come to you. You may be right in your original inspiration that this story is about a black-haired young man, but consider the possibilities -- particularly if it's hard to write. Maybe it's a red-haired middle-aged woman? And introduce them to each other. One idea may not be enough to sustain a story, but two or three or four could pull it off.
6. Outline your stories to ensure that your idea does sustain a story. A rule I discovered when one too many stories die. Your English teacher does not have to approve of the format; you just have list all the events in the story. (I consider it going through a foggy forest, blazing the trail, to ensure that there is a path before I actually start to build it.)
7. Write. You actually have to put words on paper to get anywhere. So do it. Do it regularly. Daily quotas help, I find. And don't get it right, get it written.
8. Write fat, revise lean. This rule has actually gotten less use from me over the years. But when you are in doubt whether to put something in or leave it out -- put it in. It's easier to strike something in revision that dredge up the memory of what that bright idea was that you foolishly left out. Besides, this way you can work on invention and selection separately. They're two different skills and it helps to develop them separately before you get them to work together. (Which they will do, in time, without any effort on your part, as you get better at both.)
9. The story comes first. If you want to send a message, go to Western Union. Do not sacrifice the aesthetic necessities of your story to send a message. Or for any other reason.
10. Is this elf necessary? Many writers succumb to the temptation to slap some cosmetic differences on their humans and call them something other than human. Never let your world-building contain non-human characters unless you know why they can't be human. (Rule # 2 is useful here.)
11. Finish what you write. It is very, very, very easy to have a stack of half-finished stories. If you do work on two -- or more! -- projects at once, ensure that if you drop one, you circle back to another. Going merrily on will ensure that you never finish anything. You are not juggling stories; the force of gravity will not automatically bring them back to your hand.
And finish revising a story, too. It may take a number of shys, but it's not done until you finish revision.
12. Let a story cool before revising it. This way, you have a serious chance to read what you actually wrote, instead of what you thought you wrote. The difference can be startling.
13. Remember rule 5? It still applies when writing, and even revising. Especially when revising. You want to be able to throw stuff out when it doesn't fit the story.
14. Write what you like to write. If a story heads off into something you don't find fun, there's no law compelling you to even start writing it.
n=14. I think that will do.