I was over at Joe's place recently (www.jakonrath.com/phpBB3/), and another writer was asking about how you plot a story, whether you outline, or just free-form it, etc. Joe said (paraphrasing here) he sets up the main character and their goal, then throws obstacles at them to keep them from reaching it. My answer was that I tried free range writing and it didn't work, so I outlined.
I suspect Joe thinks I'm a wuss.
I'm not going to tell anyone to do anything my way - except maybe fold towels. But here's what worked and didn't work for me.
My first novel is a 90,000 word story of a girl who runs away from home and discovers true love, which is not what I wanted her to do, but that's another post. The real problem with this book was that I didn't have a clear sense of where it was going or what it was going to do when it got there. I had some vague notions of things I wanted her to do, vignettes that I wanted to include. So I focused on those, and strung them together with verbal baling wire. And it shows. Thin, sparse, unbelievable deus ex machina events to get her to meet X, then Y.
Don't get me wrong, it was well-written. I can put a verb with a noun, and my adjectives are things of beauty. But it was crap. I'm using it for parts these days.
When I started writing my murder mystery, I was afraid of having any holes in the plot. I didn't want any mismatched clues. No Jessica Fletcher moments. You know, "Ms. Carline, you said in Chapter 37 that X couldn't have known Y because of Z, but in Chapter 3, X and Y are having a conversation." Ack.
So I outlined the plot - in an Excel spreadsheet, like a true former engineer. I described each chapter in as much detail as I needed, listed the clue revealed in the chapter, the characters appearing, and the day. I found, in my first novel, that I sometimes have a problem with time. My characters would do something a week earlier, then talk about having done it yesterday. The spreadsheet kept my corpses from rotting too long, and kept my characters from having full-proof alibis.
Now, I didn't always adhere strictly to the outline. Sometimes I'd stray, but I always knew where I needed to come back to. The important thing, for me, was that I felt I had a cohesive novel at the end, at least from the mystery point of view.
I'm currently working on the next book in the series and I'm outlining it. It may not be what works for everyone, and it may not work for me in the future, but it's what works for me now.