Writing advice from Zadie Smith: write it then put it in a drawer.
When you finish your novel, if money is not a desperate priority, if you do not need to sell it at once or be published that very second -- put it in a drawer. For as long as you can manage. A year of more is ideal -- but even three months will do. Step away from the vehicle. The secret to editing your work is simple: you need to become its reader instead of its writer. I can't tell you how many times I've sat backstage with a line of novelists at some festival, all of us with red pens in hand, frantically editing our published novels into fit form so that we might go on stage and read from them. It's an unfortunate thing, but it turns out that the perfect state of mind to edit your novel is two years after it's published, ten minutes before you go on stage at a literary festival. At that moment every redundant phrase, each show-off, pointless metaphor, all of the pieces of dead wood, stupidity, vanity, and tedium are distressingly obvious to you.
Top notch advice. I'm currently working on a (mostly visual) redesign for kottke.org. I pretty much finished the Photoshop part of it two months ago and haven't looked at it since, hoping that the distance will give me some much needed perspective on whether the new design is any good or not. I've used this technique on the past couple of designs as well...if you have the luxury of the extra time, I'd highly recommend it.