I'm still trying to re-write my fantasy story, and have developed my own system (I can't claim it as unique, as I'm sure it isn't).
First, write a story.
Second, print out said story and read it again, preferably after letting it sit for a few days. Mark on the manuscript where there are errors or where things need expanding or changing for the sake of the story/plot.
Third, create a new second draft, starting from a blank word document, using your notes and incorporating all the necessary changes from your notes.
Fourth, go back through this second draft, and think about phrasing and correct any errors.
Fifth, finished. Share with friends and have a night off.
I'm currently at step 3, and it is DIFFICULT. I'm out of my comfort zone now, writing with my editor's hat on (rather than my creative hat, which has daisies and paper windmills and bubbles coming out the top...). I'm determined to get it finished, I really need to get into the routine of finishing what I start.
And on that note, let me tell you that last week I workshopped a story from the "Corrie Flint" canon at Speculators and spent a little time outlining a plot. This might be my next big project, but I'm aware that I still have so many things unfinished, so near to completion.
I'll let you know how the re-writing system works out. For now, back to the grindstone.