I've finished my story. What happens next?

Karen Miller, author of the Kingmaker Kingbreaker and the excellent Godspeaker series' (plus lots of other things), has posted on her Livejournal page some advice on what to do once you've finished your magnum opus:
And why do I give it now? Because there is a massively humungous difference between celebrating the achievement of having completed the story … and actually having a manuscript that’s ready to submit. Being brutal, it’s almost unheard of for a seasoned professional writer to produce a perfect first draft. And that means the chances of an up-and-coming writer of doing so are pretty much Buckley’s and none.

So the first thing you need to do is sit on that completed manuscript for a while. Get back to your life for a month, six weeks. Stop living inside your head and rough and tumble it in the real world. No writer can ever achieve a true and objective distance from their own work, but it’s possible to come fairly close if you put the story down, put it away, and fill your mind and imagination with things completely unrelated.
Source: Karen Miller