If you choose to self-publish, you will find yourself with a few weeks of almost-free time while the printers are figuring out how to print your book. It is during this time that you must take off your author hat and put on your publisher hat. It is time to think in terms of your book as a product rather than your book as an act of creation.
Your book will be a financial success to the extent that you promote it. This it true whether you self-publish or Doubleday publishes it. The advantage of self-publishing is that you are under no illusiuons as to who is spreading the word about your new book.