You can write the best book you can, and that might still not be enough. Appeal isn't something that most writers can't strive for or identify. It's something even the best agents and editors can't always identify.
Ask your editor or ask your agent to find out what the house's goals are for your book before it comes out. Get some sense of expectations so you are prepared.
Ask your agent to set up a meeting with either your editor or the marketing department of the house or both so you can find out what they're doing, what they aren't, and what you can do to help.