One thing I think about is the beginning. The first story I wrote, "The Apartment Mystery," did not end up being the first story in the chronology (it's #4), but I've always felt it worked best as the first story for people to read.
On one hand, of course, the Sherlock Holmes stories weren't chronological in any of the books. On the other hand, those books weren't stealth novels, and it will be the only one that's out of sequence.
Then Laura Stanfill wrote a post called, "Writing Challenge #10: Keep an Eye on Your First Chapter," about making sure, throughout the process of writing a book, that the first chapter is doing its job "setting up the story, setting and characters."
I also think about this in terms of Mindmistress, a web comic I've followed for almost ten years now. Al Schroeder is the artist, and he posts three pages a week. Over the years, his art has improved from this to this.
But he knows that people often start a story at the beginning (even a web comic where there are separate storylines and you can jump on later), so he's been going back and redrawing the panels of the very first story. Not the other early ones, but he knows the first chapter is especially important.
And there's also the example of The Sun Also Rises. F. Scott Fitzgerald read it before publication and told Hemingway to remove the first chapter completely and just start with Chapter Two. Hemingway agreed (he never forgave Fitzgerald for being right, though), and the beginning of the book is a classic ("Robert Cohn was once middleweight boxing champion of Princeton...."), almost as famous as the end ("Isn't it pretty to think so?").
A friend recommended Père Goriot by Balzac once. I read the first few pages, then I tossed it. It was all description of the house and grounds, no characters, no action, no hooks. This was not for me (there's a reason I don't subscribe to Architectural Digest).
Or you can read the beginning of The Portrait of a Lady by Henry James to see how you can describe the setting and the characters all at once at the beginning of a book. It's a perfect beginning to a great novel..
But I am still convinced that "The Apartment Mystery" is doing its job. There's a lot of work yet to be done on the rest of the book, but I've made the edits to the first chapter, and here it is (or you can get a printable version here).