I write in...well sections I suppose you would say. I create a world, I create a story, I create characters, then I look at each of them and figure out, this of course causes each of them to change and grow. Once I've finished that step, I start to put them in place, the setting, the characters, the story and I make a small section and then read/play through it and see how it works, I then make changes as needed.
I guess you could say my writing style is very...alive, it's constantly flowing and changing and something I was convinced was set in stone a week ago, may not make sense later given changes in circumstances. I suppose a lot of this comes from my experience as a GM and seeing how my players react to my worlds and stories, it really makes you quick to adept and also makes you not plot to far ahead.
I hope that makes sense, had a long day of manual labor and my mind is not with it at the moment.