Things you should know about fan fiction before you post. With lots of juicy extra links that you NEED TO READ.

1. Grammar and spelling count
Most of your more discerning readers won't get past the first paragraph if you don't bother with them.

But since no one is perfect...

2. Get a beta reader
A beta is someone who reads your fanfic before you post it publically. They'll point out grammar and story issues and mistakes, and because, unlike you, they haven't been slaving over the story for days or weeks or months, they'll have fresh eyes and notice things that will slide right past you as you reread for the 53rd time. They're invaluable, and you want one or two because they'll make you look better.

Also, get someone you trust to give you constructive criticism. It's hard for a lot of writers to hear anything less than positive about their work, but trust me, it'll make your writing and your stories stronger in the long run. And it's good to develop a bit of a thick skin, because you're oing to need it once your work is in the public eye.

Some places to find a beta reader include TFN's Beta thread and the Star Wars Beta Readers community on Livejournal.

3. Start small
If you're new to fanfic, it's best to start with a short piece. Even if you have a giant, multi-chapter epic knocking around your head, starting with a short, self contained story will let you get a feel for how this all works, and what reader reaction may be to your ideas and style. That giant story may be a tad overwhelming for you if you're new, so get some practice in. You don't want to enter the Boston marathon if you're not sure that you can run a mile yet, right?

Keep in mind, however, that 'small' does not mean two paragraphs. I'm still boggling over that one.

4. Don't ask for money
We've covered this before.

5. Know where to post it
As in, not here.

Further Reading Or, people better at this than I...
- Dr. Merlin's Guide to Fan Fiction. The internet classic. If you only read one thing linked in this post, it should be this.
- Avoiding Mistakes in Fanfiction Writing: A Beginner's Guide. If you only read two things linked in this post, this should be the second one.
- Wookieepedia: Fan Fiction, including common types and terminology in SW fanfic.
- Chilling Effects: Frequently Asked Questions (and Answers) about Fan Fiction. The legal side of things.