Today's writing hack (just in time for Halloween): "Graveyard" files.
As I write my way through a 5-book urban fantasy series, I find myself rewriting and ripping out whole chapters of books. Whenever I do that, I save the old chapters in a document called the book's Graveyard. It's where old content goes to die. I organize it by the chapters they used to be headed under.
Why do I do this? Because sometimes you realize that an old chapter you axed had something of value. Maybe there was a great description in there. Or you changed your mind about a subplot, so you want to resurrect an old scene. It's pretty easy to just "dig" into the Graveyard doc and resurrect it back into the main story.
I suppose I could also just make a bunch of different file revisions, but with this system, I have all my old content in one file. I love my Graveyard files...they've saved me from a lot of unnecessary rewrite. And sometimes, it's nice to be visited by a ghost from the past.