Look for a publisher that best suits your book's genre. If the book is fiction, seek a custom publisher that specializes in fiction and so on. Publishers like Outskirts Press not only publish books, but offer marketing help as well. Sending your manuscript to the wrong publisher can result in an automatic rejection.
Seek a publisher that specializes in business publications should you need to have business materials published. Faulkner Press is one publisher that specializes in business materials.
Use a custom press that specializes in text book publishing if your book is a text book. XanEdu is a great example of one of these custom publishers.
Publish your own book. Purchase software such as those created by Adobe, and set your own manuscript. You will have to do your own marketing as well, should you go this route, but there are books and sites that can help.