Some of the commandments apply mostly after you've been selling regularly. But learn them now. That way you'll be working toward and prepared for the best--a pretty good definition of ambition.
1. Put Thy Work First - Not the Market
Write the stories you care for, you get involved with, you would like to read if someone else had written them. Write from the heart--at least on the first draft.
2. Thou Shalt Not Take the Names of Thy Editor, Publisher of Agent in Vain
The writer hasn't lived who hasn't become upset with his editor, agent or publisher, and spouted off about them with a few choice names. These moods generally pass...keep your name-taking-in-vain reasonable private. Publishing, after all, is not a large industry.
3. Keep Sacred They Work Schedule
A schedule shouldn't be a straitjacket. But by making it a genuine priority, you slowly train your mind to be ready to write fiction when your calendar allows it. This subconscious preparedness can be a powerful asset in writing enough pages to improve steadily.
4. Honor Thy Reader
Early work of fiction makes an implicit promise to its readers. You are obligated to keep that promise, whatever it is, by not starting your story in one mode and finishing it in another.
5. Thou Shalt Not Kill as an Unnecessary Plot Device
Sometimes writers, when they think the plot is sagging, give in to the temptation to enliven it by blowing up something, or by killing off a character, perferably in pools of gore. The problem with using this device in fiction is that it seldom works.
6. Thou Shalt Not Commit Adultery as an Unnecessary Plot Device
Ditto everything just said about murder. Juicy sex won't save juiceless prose.
7. Thou Shalt Not Steal Too Much
Writing the same plots, characters and settings over and over again doesn't challenge you. You get stale. Limit the amount you steal from yourself.
8. Thou Shalt Not Bear False Witness Against Thy Characters
Your characters have-or should have-integrity. They may be noble, summy or anything in between. It's your job as a writer to witness this person's integrity, understand it, and not make him violate it.
9. Thou Shalt Not Covet Thy Editor's Job
You are the writer. She is the editor. . .Let the editor edit.
10. Thou Shalt Not Covet They Fellow Writer's Goods
Try to keep envy within reasonable boundaries. You are you, and your career is your own. Others' successes don't detract from that--at least not if your goal genuinely is to create the best fiction you can. (Refer to Commandment 1).
(Adapted from "The Ten Commandments Redem Your Writing: Follow These Steps and Find Salvation," by Nancy Kress, Writer's Digest, March 1996).