The Plot Thickens And We Get Stuck In It -- or, how the bloddy aitch do I get from here to there?
All right, you have this great idea, and you sit down and really work on it! Suddenly you realize that you haven't the foggiest where it's going, really. (Aren't you glad you didn't start posting it right away?)
Wasn't it all there in your mind when you started? What happened to it? These characters aren't behaving, heeeelp.
Time to do some mind-surfing. Where do plots come from? You started with some kind of what-if. Unfortunately, the details were less clear than you thought, there wasn't enough behind the warm, rosy glow of inspiration to fill out a story. So go back and what-if some more. Explore possible branches and choose those that give more life to the story.
Write some more anyway. Let yourself just rip through a few thousand words of whatever and see if something turns up! Even if you end up going back, tossing out half or all of it, sometimes writing through a few possible situations will jar ideas loose or firm up something that was too vague.
Read back over what you already have. Maybe you left yourself a clue. Is there something that didn't really contribute much to what was happening but just had to be there? What could it mean? Have a good what-if on it.
Relax and visualize scenes, let your characters act out the odd bit while you sit back with a cup of coffee. Think of their goals. How could they relate to a satisfying ending, and what has to be done (by the characters) to realize those goals?
Possibly the beginning is what's wrong. Starting in the wrong place, not setting the scene or getting the character established before plowing into the action can make it hard to move on.
A time comes when I can see that what I have written so far is only something to base further thought on. The world of my story needed time to grow. Like a good soup, it takes a while. It needs a litle more of this, a bit of that, and some time to simmer slowly.
Going back to earlier chapters, I hunt down awkward bits, consider how things might be clarified or deepened. All the time I do this, the previously written parts are becoming solider. They foreshadow future chapters more strongly. This in turn throws shadows backward that force me to reshape the older parts even more.
Sometimes I don't seem to be going anywhere, but the reciprocal shaping process eventually swings into more of a forward mode.
I release my grasp on the already-written words that lie like a curtain between me and what must be. The "real" world begins to show through. More and more it becomes visible, melting away the thin layer of words and replacing them as fast as I can cut, paste, delete, and type.
"There, see? That was what I meant to say," a character says, looking over my shoulder. "Let's move on, ah?"