Paul Graham wrote one of the best essays on writing in March of 2005. I encourage you to read it. In fact, print it out, post it on your bulliten board, and read it every time you start a new writing project.
Writing, Briefly:Whether it's a grant application or a novel, Paul's advice applies.
(In the process of answering an email, I accidentally wrote a tiny essay about writing. I usually spend weeks on an essay. This one took 67 minutes—23 of writing, and 44 of rewriting.)"
Follow the link to Paul's site.