Jay Lake, author of the new clockpunk novel Mainspring, talks about “Plot dynamics 101” in his blog. His main point relates to balancing the tension between “giving the reader enough information that the ending will ring true, and not giving them so much information that the ending will be all too obvious in advance”
He mainly talks about science fiction and mystery short stories, but on a basic level I think it’s possible to think about any type of story in these terms. One solution he says is to set up a “slightly more obvious false ending, so when the true reveal occurs” the ending seems both novel and rational.
I like the idea of a “reveal.” It’s like a sleight of hand magic trick. It works through misdirection. You make the audience think the coin is in one hand, when it’s really somewhere else. Now you can make it disappear, and if you like, reveal it coming from somewhere unexpected. When done well, the effect is always entertaining.