Once you’ve written your story, I think it’s important to let it rest for a while. It’s almost as if you’ve planted the seeds and now you have to let them get on with the business of growing. If you try and edit immediately after finishing the story, it’ll be very difficult because at this stage you’re too close to what you’ve written. You can’t ‘see the wood for the trees,’ as it were, (or words!), but by leaving your piece for a few weeks or even months, you will be able to see the story through fresh eyes, so when you return to it, you should have a much clearer idea of what needs to be changed.
I did this with a piece I wrote a while back. It was driving me crazy at the time as I was trying desperately hard to get it right, so I put it on a writers’ forum and absorbed the ideas proffered by the members; but then I started to struggle as I still couldn’t really understand what needed to be changed. I now feel ready to go back to it as my head is clearer.
I’m hoping this is the same with novel writing as I haven’t revisited my novel since I finished 50,000 words in November. There were bits of the story, especially near the beginning that I didn’t like too much at the time of writing, but now I feel it’s time to edit; enough time has passed!