1. Shake off "Impostor Syndrome"
Everyone communicates, and a lot of people write, but few people dare to call themselves "writers". If you feel like an impostor, take a deep breath and remind yourself of your unique purpose and how important it is. Or take on a fictional persona and write through that mask.
2. Conjure Your True Voice
If you're at a loss for words, try meeting a friend for tea and talking your way through the material, or even talking out loud to yourself. Your spoken words might not be publishable, but once you've got 'em down on paper, you can edit to your heart's content.
3. Write it as a Letter
Submitting written work can be scary--especially if it's going to be read by The Powers That Be. But you don't have to think about those Powers when you're writing; in fact, it's probably better not to pay them any mind until the last few editing stages, after you've already squeezed out every last idea and captured it on paper. So when you're still writing, why not imagine you're writing a letter telling your closest confidante about your project? Try starting your work "Dear ____", and you might tap into a fountain of lovely, loose conversational prose.
4. Detach Your Ego
If stage fright derives from fear--the fear that if the work fails, we fail--we need to disconnect ourselves from the work. When I play pool, I don't care if I win or lose, because I'm not A Pool Person--but beat me on the air hockey table and I'll be grumpy, because I'm invested in the game. Realize that people reading your work are just as self-centered and will most likely not draw any permanent conclusions about you from your work.
5. Plunge Into the Scary Parts
What are you afraid of? Spelling poorly? Weak transitions? Well, go ahead and deliberately spell every word incorrectly, write without transitions, don't use any punctuation--do everything you're not supposed to do, and have fun doing it! Draw caricatures of your writing demons, put the dreaded failure behind you, and move on.
6. Lower Your Standards
There's really no reason to worry about editors, teachers, critics, bosses, and what they think until the last stage of revising. Until that time, indulge yourself. Don't correct anything; write in slang; write 3 pages in 15 minutes; leave notes to yourself, like ADD DETAILS HERE or FIX THIS LATER, throughout your work--anything that makes it easier to write.
7. Sidestep What Blocks You
Don't let one part of your writing stump you for long. If it's bugging you, just skip it and move on to an easier, more appealing task. If the introduction isn't coming, jump right to paragraph two, or page 23. If you can't think of anything to say in one section, just skip merrily along to the next part and let your unconscious work on the hard stuff for a while.
8. Stop When You're On a Roll
When writing is a struggle, you'll naturally want to stop. But if you do, you're rewarding yourself for not writing. Try sticking with it--and then quit when you're on a roll, so that next time you'll be eager to return to the work. Or start writing when you know you have to do something else in 45 minutes--as soon as the pressure's off, as soon as you say "well, I know I won't get anything done in this little bit of time" you're free to let your creative juices flow. Waves of inspiration will come and go; the trick is scheduling your work to take full advantage of the tides.