What I've been doing lately, since mostly what I'm writing is 'thon assignments:

I start with *some* inspiration, a point of entry or an emotional arc, or something, and then I start thinking it through in my head. I've done this a lot lately; thought about a fic for several days and developed the basic functional framework -- the various things that will happen (which are mostly inward things since I don't write plot-heavy fic) in the story.

Then once I start writing, I generally have some idea of what the emotions are... generally, since I'm writing 'thon fic, I have somewhere I *need* to end up, a sort of given resolution, and then depending on how okay I am with the pairing/situation in question, I may need to do more or less work to find the emotional setting in which it would be okay for that to happen.

But often when I'm writing I'll get stuck on the way from point A to point B and wonder *why* the character is doing this, and have to sit back and take stock and try to figure out where exactly she is emotionally.

So. Uh. I don't really know, but obviously writers need to babble about writing rather than *actually* writing, so there you go.