Heh, despite last week's helpful posts on discipline, I still failed to post this on time. Life is a learning experience, yes?
First drafts are my favorite part of writing, without a doubt. Forget the agony of revision, the pain of rewriting and trying to fill plot holes; I like the rush of pure creation. It used to be that I agonized over first drafts too, wanting every sentence to be a polished gem (or something) before I moved on to the next one. Then I started doing NaNoWriMo, and, well...things changed. My first drafts are great rambling messes now - but I actually write them, instead of staring at the page and trying to decide whether to tag a line of dialogue with "she said" or "she exclaimed".
I've mentioned outlining, but I don't usually outline before a first draft. I've mentioned discipline, but I'm very undisciplined when writing a first draft. I put off writing until the words are literally spilling out of me - until I'm scribbling down phrases and paragraphs on nearby scraps of paper and my comp sci notes and the grocery list - and then I lock myself in my room for hours at a time and blurt the story out, either by hand (if it's short) or on my computer. Eventually, either I finish or I have to go do something else (like go to sleep).
Once I have a first draft, that's when the real work begins.