First drafts are tricky beasts. They always take longer than I think, and they're always rougher than I want. Every writer seems to attack them in their own way, but the biggest lesson seems to be: no matter how you do it, just finish the gosh-darned thing. Write it in a way that's easiest for you.
For me, it's dialogue. As a result, parts of any of my first drafts read almost like a play. That's fine. All the details get added in future drafts. After all, I want my manuscript to be a lush portrait of the events, not a black and white sketch.
Since I write mysteries, I have to know my plot before I begin. I know who died and why. I know who did it. I know most of my sub-plots. You'd think I'd be fine, wouldn't you? HA! I'm always amazed at how the story winds off in unexpected directions or how characters show colours I wasn't expecting.
Perhaps other writers, far more talented than I, can write better first drafts. I'll stick to what works for me. After all, in that marathon of writing the first draft, it's crossing the finish line that counts, not how pretty you looked getting there.
Now, if someone could just tell me how do get these characters to shut-up....