I couldn't agree with Jeff's suggestion of "starting ugly." When I used to teach high school English, my students would painfully try to eek out perfect words and sentences for the first draft because they just wanted to be done with it.
In turn, they absolutely hated the writing process and usually had to do 2-3 rewrites anyway based on my comments and suggestions (boy, did they used to seethe when I returned their "drafts" that they though were final copies!).
I have spoken with a lot of writers that do the same thing. Where in the world did so many of us get the idea that you can create a perfect first draft? Maybe because we fear failure and see an ugly first draft as a failed attempt?
I wrote about how "writing ugly" helps me have mega production days on Denice Hazlett's site.
What's your highest word count day to date? Pick out a weekend day or upcoming day off and see how many words you can put down when you let yourself write ugly. You'll be shocked--I know I was!