the 12 Biggest Mistakes of First-Time Authors

from Roger C. Clarke's Published & Profitable
the italicized text are mine :)

1. Unrealistic expectations
Thinking book equals money might find you in that relationship stage where you think the one you're with is a god who later turns out to be human. Well, that's life!

2. Writing without a contract
Apparently, you must prepare instead a proposal and a few sample chapters. Personally, just keep on writing. Don't give away the goose but let them have a glimpse of the golden eggs.

3. No agent
Get one and let him or her do the talking. You're a writer. Question though, what if you can't afford an agent? Seeing that nothing stops you from not hiring an agent (as of now), learn the tricks of the trade. It won't hurt. Experience is a pretty good teacher.

4. Weak Titles
What with people's attention span?

5. Title versus series
Just leave room for future projects.

7. "Event" Writing
Block time off to write daily instead of shutting the world out in order to write. Writing is a discipline. Even if you've got talent and a writing Muse, if you abuse it or don't use it, well, as the Sixpence None the Richer song goes, "There she goes..."

8. Self-editing
Write in white heat. Let the editors edit in cold blood.

9. Failure to promote
Get out there. Publishers apparently are not publicists.

10. Failure to backup and save
Murphy's Law states that everything that could go wrong will go wrong. This law operates during the most crucial projects of our lives - cramming your thesis, preparing a slideshow for your defense, etc.

11. Failure to plan future profits
Don't stop at your first book. There are lots of opportunities out there. You just have to look for it.

12. Failure to consider options
As what Phoebe would say, it makes good sense to back up your backup.