1. Find a good editor and treat him/her well. I don't know if you are planning to publish the traditional way or whether you are planning on self-publishing, but regardless, having a good editor is one of the most important things *any* author can have.
2. Find 2-3 readers who will point out problems.
3. Self-publish. IMO, traditional publishing is almost as effed-up an industry as higher education.
3. Self-market. Even if you go the traditional publisher route -- unless you are a "name," you're likely to get short shrift from the publisher in marketing your book for you. Get a copy of John Kremer's
1001 Ways to Market Your Books.
And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove what is that good and acceptable and perfect will of God.
Romans 12:2 (NKJV)