I've posted some writing advice by Chuck Palahniuk in a past post and found the gem below and thought it worth sharing:
"Let yourself be with Not Knowing. This bit of advice comes through a hundred famous people, through Tom Spanbauer to me and now, you. The longer you can allow a story to take shape, the better that final shape will be. Don't rush or force the ending of a story or book. All you have to know is the next scene, or the next few scenes. You don't have to know every moment up to the end, in fact, if you do it'll be boring as hell to execute."
People who read this blog closely will see a contradiction between this advice and my advocacy of establishing a structure before you write. And I'll admit, there is some inconsistency, except that while I believe establishing structure prior to writing to be incredibly important, especially to writers with day jobs, families and other parts of life. It gives you a road map to follow and makes it easier when life forces a writing break to come back and understand where you've been, where you are and where you are going.
However, the road map should never be dogmatically followed. It's a guide and open to revision or tossing in favor of a new road map at any time during the process.
A road map is also not a first draft. It's an examination of your idea and placing parts in places so the flow and structure of the story can be seen, played with and understood.
So anyway, enough preaching. I like Palahniuk's advice because writers should always be looking for ways to make the story and writing better as they go. With a road map you aren't building the car as you drive it, but you have a much better sense of what you're doing and able to create as ideas and inspiration hit.
So create a structure as a road map, but as you write, focus only on the thing you are on and the next scene. Sometimes altering the route leads to finding a real gem.