There really is no substitute for experience.
For instance, if I were to go back and do it again, I might have rethought the way "The Village That Sleeps" begins. Then again, I might have decided that the way the book opens was the best option, dramatically. And this is my chief concern.
However, Amazon chooses a chunk of a book to show for its "Look Inside" feature and I always check them after the appear (the author has no control over it) to see how much of a preview someone is given. The first two books start off right into the action. There's strange scientific experiments and dangerous mountain climbing to be found there. But, the third book starts with... making porridge. And serving porridge. And a bit of very chaste flirting. Part of me wonders if that's not quite as "hooky" as previous books. They don't even get to the bit of business with Helen and the porridge which I think is sort of fun from a character standpoint. Oh well.
Then again, some people might really like porridge making and flirting. It could be a whole new audience.