After deciding to use the first scene of my original story as the start of the new version, I realised that quite a few of the early passages were good enough to reuse wholesale. So far I've written about 2,100 new words and recycled about 3,400 words of the original story. As I get further into the new version, I expect I'll be using fewer passages from the original story, as I'll be adding new twists and turns to the plot before the first big significant event.
Having not tried working this way before, I've been very happy with it. The outline in my head is very similar to the one I was thinking of when I first tried writing the story, although I'm a little unsure how much development I'm going to give to the secondary romance compared to how I originally planned it.
I've also thought up a few more secondary and tertiary characters that the original was lacking, which will hopefully flesh out the story rather than my needing to go into details about how the world came to be the way it is (my big stumbling block first time around).
How about you? What new writing techniques have you tried? How have they worked for you?