1. Bring a unique element to your story. It can be tempting to write the "same old thing" sometimes.  Perhaps an you read a story you enjoyed and admired, and you wanted to write one like it.  Beware of doing what others have already done: who wants to read a carbon copy of the latest idea craze.  This can be especially dangerous on fanfic lists.  Make sure that your story has a purpose, a goal, an objective different than that of other stories, something that will entice your 'fans' to read it. 2. Sap can be good.  Or... it can be evil There's nothing wrong with rewarding the audience of your arduous, angsty tale with a little good feeling.  Just make sure to use it in moderate amounts, and whatever you do, make sure sap isn't the basis of your story.  Stories need villians, emotional and physical conflicts, to draw people in. Flowers and gushing words from your hero's mouth might seem nice, but take care not to turn what has been a bittersweet tale into a sugary-sweet mess. 3. Bring your characters to life Original characters can bring a lot to your story; they can make it or break it, in some cases. Nothing is more annoying to read than a two-dimensional character: someone blindly evil, for example, or someone who only brightens days and brings smiles to the character's faces. No one is all good or all bad, and no character should ever bring all good or all bad  to your fic.  Give your character background, motive... it doesn't matter if it's an ally, an enemy, a baby, or a new love interest.  Be proud of your characters, and show all their sides.  And for all of our sakes, avoid Mary (and Marty) Sues. 4. Small steps... Exercise subtelty in all things: plot, action, and especially conversation.  Remember that you can say a lot in a story without having the characters ramble on for pages.  This is especially easy in romance stories -- writers, as Jack, Sam, and the others profess their undying love and devotion (and then proceed to jump in the sack) stop and ask yourself: "If my story was on TV, can I really see them saying this?"  Utilize other writing tools: set the mood with your own descriptions.  Let the characters speak for themselves through body language and thought. 5. Change is a good thing. A good fanfic, just like a good episode, will illustrate some type of change in the character(s) it focused on.  It will introduce a new aspect of that 'person's' personality for the reader to think on, or it will chronicle a change in the character's attitude.  Remember that your story is a journey; the character should emerge from it a changed man (or woman) for it to be truely satisfying. 6. Pace Your Story A work of fiction needs dialogue, action, and introspection; however, try not keep from clumping them all together.  Shy away from pages of 'he said' 'she said' conversation.  Break up long passages of text with a few spoken lines.  Intersperce action and thought, so we know not only what is being said and done, but what is being thought. 7. Know Your Auidence Know what they will accept, and know what they will need to be convinced of. 8. Made in the U.S.A.... Keep the setting in mind, especially when writing dialogue, and especially if you're not familiar with American English.  Be aware of the nationality of your characters, as well as the slang they would and wouldn't use.  If you find you need some help, American Beta-readers aren't hard to find. 9. Consistency This can be a big problem with Works In Progress. Did you rate your story G?  Then avoid graphic scenes.  Is it classified a SJ story?  Then you might want to steer clear of smarm.  This relates to #1: have a goal, a purpose, to your story, and stay the course. 10. R-E-S-P-E-C-T Exercise respect for your characters, and the reader as well.  Remember that your story will probably remain in the reader's mind in some small part, and could influence their opinion of a character or even the entire show.  Use your power for good, not evil.