This is how I got the idea for my WIP (finally figured out what that meant). I studied a specific sort of interesting person (won't be specific). I found the problems of living in the skin of these specific people. I extrapolated various situations that could happen with the possible gas milage that a novel would need. I don't believe all ideas can sustain a full length book. I had come up with something appropriate to a novel length book. Once I had a decent Idea which I knew I could move for 300 pages, I outlined the beginning. How would I intro the person, how would I intro the problem. With each section, I pulled the plot threads out-- like building an expansion bridge over a river-- forwarding the plot. Since the characters were developing, in the meanwhile, their changed personalities told me how they would react and so on, and what they would do. I am now in a part where the characters have decided to run by themselves for a while. As the author, I keep them pushed back into the roles which they can't really move far from -- okay now this is the fascinating part, I have found, they push on their own, to grow out of their predestined roles. This is really a character driven book, literally.
This story is the second of 3. The first is at about 77 pages, this one is at 150, the 3rd is at 0, (oh, they will be short novels, less thn 250 pages each) but with each page, I get more of an idea on how to proceed on the other 2. I know the entire story of the first, for example. I know what happened to the main character, as I do in this 2nd novel. I also, strangely enough, have more of an idea about how to finish a book I started and threw aside about 5 years ago.
I'm trying to get into a mode where I can actually do maybe 5 pages per day. Often though it is like developing muscles you've got to feel the burn and then take a day off to allow the new muscle fiber to grow.
Oh-- also the Bob Dylan song "Hard Rain" -- I know my song well before I sing it.
I know the stories, and recite them, over and over in my head, looking for flaws. I also read the MS again and again for stuff that doesn't work. I feel that if you can tell a story in a shortened version (like a campfire story) and it sounds good all the way through, having the perfect "scary" ending, then you are good. As I said though, I build my span as I go, so I have to keep adding onto the story. The way that I corral myself in, is that right while I am writing the beginning of the book, I write the end. Knowing the ending really gives me a clue of how the characters must travel on the road I create. It is kind of sad, especially if the characters are "doomed" but this is a creation for an audience who need to read it forward, while I have the luxury to write it backward.