[found on fictionfactor.com; by Lee Masterson]
Effectively Outlining Your Plot
“Have you ever had an idea for a novel, and then just sat down and began writing without knowing exactly where the story was going?
It happens to everyone at some point, but most people begin to realize that the events in your plotline get confused, or forgotten in the the [sic] thrill of writing an exciting scene. There are those who continue to write on, regardless, fixing any discrepancies as they work, or (worse!) those who do not check that events are properly tied in place to bring their stories to a satisfying conclusion.
And then there are those writers who believe that creating a plot-outline is tantamount to “destroying the natural creative process”. The belief is simple; by writing it out in rough form, you’ve already told the story, so the creative side of you will not want to write it again.
Whichever type of writer you are, creating a simple, inelegant outline to follow s not the same thing as already writing the story, and it could save you an enormous amount of time and rewriting later.
The purpose of an outline in this case is to be certain that your storyline is not straying too far from the original idea. It is also a useful tool if you need to determine if your idea is big enough to be developed into a novel-length work, and not left as a short story or novella.
Your outline should be a simple reminder that, no matter how many events or characters or situations arise, your main theme will never get lost in the jumble of scenes.
Of course, this brings us to the problem to what was discussed above. There are writers who have a tendency to over-plot, thus really killing any spontaneity as far as the writing process goes. The biggest difficulty here is forcing your characters to go through motions that may not fit into their personality make-up simply to fit into your pre-existing, overly planned plotline.
So how do you strike a fair balance between aimless writing and over-plotting? There are several ways to accomplish this….”