When I am looking through the bookstore with some $$ burning a hole in my pocket, I look at covers that catch my eye then the very next thing I do is to read the back cover blurb and go from there. So what does that have to do with your writing?
I went to a conference at Utah Valley University recently called Book Academy and in a class taught by Lisa Mangum and Kirk Shaw. Kirk said that you could write the back cover blurb before you begin the actual book. You have the Who, Goal, Obstacle, Consequence of Failure right? Then write your book. Go back and read the blurb you wrote and check to see if it still applies.
Are all the key elements in the book? Would a reader fill like you kept your word and delivered on the story you promised? If yes, Great! If not, go back and revise. Flesh out your weak points and sharpen that climax.
I'm going to try this for my NaNoWriMo book. Have you done it before?