Found this on the web. I thought it was interesting and helpful. Liked his caution about “So then she decides to…”
Stephen Gallagher wrote:
It comes up frequently in the “how-to” books and it’s a favourite piece of jargon with the non-writing, note-giving executive. But what exactly is a story’s “spine”?
The spine is the essential information that links in a logical sequence to deliver you to an ending that, if the logic is hard enough, will seem inevitable even if it comes as a surprise. Here’s a test for a story spine; link every scene with a phrase like “So then they have to…” or “But they can’t because…”
Beware of phrases like “So then she decides to…” It should be, “So then she has no choice but to…” The Americans call these “beats” – they’re the significant pieces of new information, the points on which the story turns, and you should have a steady progression of them. I hated the term the first time I heard it, but it’s grown on me; not least because it characterises the narrative process as a steady march forward with an unforgiving sense of drive. We’re not allowed to be as random in stories as we can be in life. Coincidences are OK only if they work against your characters, never for them. Stories are machines; everything works with everything else but all you see from the outside is the overall motion.
Outside the spine, everything else takes the form of enhancement or qualification. In prose, you want to describe a locale? Look at the spine and find the point where it can be included as a relevant aside. Do it then and not before. In a script, you want a character to talk about his childhood? Then identify a point where he’s going to have some clear reason to do it. The temptation is always to shove everything up front, like making your audience go through the rulebook and notes before being allowed to enter the game. They should be into the game before they even realise it, and fed essential information only at the moment when it’s needed. A good narrative technique involves feeding the information for one purpose only to build on it later for another.
It’s good practice to know your ending in advance. This means knowing where you’re going, what point you ultimately plan to make, before you start. Every story has a point; not necessarily a message, but a point. How to define the point? Put simplistically, somebody learns something they didn’t expect to learn.
Here’s the source: http://www.stephengallagher.com/spine.htm