The Anatomy of a Story

Last night I saw HARRY POTTER AND THE HALF-BLOOD PRINCE. I enjoyed it. However it was waaay darker than the other movies but terribly funny.
On the way home we discussed how J.K. Rowling plotted all the books before even writing the first one.
"Well," I said. "I suppose she just got the main skeletal structure of the plot and just packed the meat on as she went."
They asked me, "Where'd you read that analogy?"
A tad miffed I explained I'd come up with it myself. Their response was heartening; "Put it on you blog."

Really, when we write a rough draft, we don't need to include details. At that point, we're just trying to figure out what the heck the characters' goals are, where the story is headed, and what problems could arise.
If we're going to compare the plot to bones, then let's compare the search for the plot as a sort of archaeology dig. Each draft after draft brings us closer to what the final draft's plot will look like.

It's during these drafts that we can also build around the bones. 'Pack the meat on'. Add details and twists.

I can assure you 100% that your first draft will suck. (How's that for inspirational advice?)
BUT it will get better.

Every new 'Bone' you uncover will provide a bigger picture of what your looking for.
Every sinew and muscle you add to give details will strengthen that plot.
Wow. Am I in an anatomy mood or what?