The key to writing on deadline is to keep writing. The only way to keep writing is to keep it very easy. The best way to keep it simple is to do one thing at a time. People are very bad at doing more than one thing at a time.

Step one:
Write down anything that might be relevant to the topic at hand: if nothing comes to mind try starting with "I will never take another course as long as I live because" or "one million dollars is a lot of money - after taxes" until you get bored silly and start doing the assignment. Don't be critical, don't think about what you're doing. Just type type.

Step two:
Go over what you have written and cross out all the duplication; you've probably said the important points several times. Count to see what you think is really important.

Step three:
Cross out all the stuff that is completely irrelevant (including the 'starter' material), when in doubt leave it in -don't think too hard.

Step four:
Put the remaining sentences in a reasonable order. When in doubt flip a coin, if you can't tell it may not matter. If you don't like the results of the coin toss then you do know what order to put things.

TAKE A FIVE MINUTE BREAK HERE

Step five:
Edit for sense: Look at each sentence and ask: "Does this say what I want it to say and do I really want to say it?" Rewrite each sentence until you can say yes to both questions.

Step six:
Check for spelling and grammar - computers are good for this - but not great.

Step seven:
Have someone else read it and tell you what they think it means. Then you fix any discrepancies.

Step eight:
Sleep on it and reread it at least 24 hours later. Make any needed changes.

Step nine:
Mail it in and stop thinking about it.