I'm obviously not a professional writer by any means, but I think the way you write now is the best way to write -- that is, free write, then go back to edit. I use that approach whenever I have to write blog articles for my company or write up documentation. I just do a massive brain dump, rearrange things in an "ideal" fashion, then go back to polish the grammar, etc.. It's way easier to organize your thoughts when they're all written out. It's VERY difficult to organize things when half of your thoughts are in your head and the other half are on paper, or so to speak. Sometimes being methodical is inhibitive.