I keep running into the same problem: Creating interest early on for what is to happen, yet writing too much, too early, believing this will create more interest. However, of course, when the incidents eventually occur, there is the obvious connection with what was written earlier. How much, or how little should be alluded to early on to avoid this?
I would agree with Sarah, write it first and then at your leisure you have the opportunity to look back on the work that you have done and to ask yourself if this makes sense (or if it would) to a reader. At that point you can fill in or omit what you will. One of the most difficult things I think that we have to decide upon is whether or not (and how much of) our research one reveals.
Great to hear from the competition (!) - Useful feedback to hear of similar problems of others. I once started by just alluding to an incident. Then added just a touch more. Which needed a bit more description. Soon, my beginning had grown so much that it had become the end and the book was finished before I'd really started. Hmm. The number of times I've started with a short snappy sentence, only to find after several days that the sentence is a dozen pages on and I am writing from the front, backwards which, as I said, progresses into the snappiest sentence of them all. The End. Right now, I'm working on a great final line in the hope it will lead to the beginning. My current problem, having essentially finished what will become either a gem or something rhyming with map, is selecting from a dozen possible ways to begin, each one able to link with the rest of the story, each one imploring to be used instead of the other. I have solved the problem and wonder if others had similar difficulties.
I had the same problem, it's so easy to fall into the trap of exposing too much too soon. My main characters past was the area which concerned me, so I thrashed it out and added small snippets of information through the chapters. And the reasons why she was so angry to start with, I used emotions, the way she talked, and characteristics to portray why she was that way.
As to the main body of the story, you want the plot to build gradually, try not to give the ending away too early. With mine, I've had two people read the first few chapters, and I kept them hanging with different possibilities, making them want to read more.
But of course the way you write your book is up to you. Someone gave me some good information, they told me to just write the book as you feel it, and then hack away on the re-writes. Which is what I will be doing.