MARKET, MARKET, MARKET!!! PROMOTE, PROMOTE, PROMOTE!!! You are 100% responsible for marketing your book. No one else will do it for you. There are so many variations to marketing. What works for one person may not work for another. However, with the vast amount of technology available at your fingertips today, learning to market your products and services is as simple as filling out forms and posting messages to bulletin boards utilized by your target market.
The idea is that you market your book so it can "keep going" in the marketplace; no marketing may mean that sales will dwindle before they need to. So, finding your niche and properly marketing to your target consumer is paramount. No matter how nice the marketing program sounds, you cannot totally rely on the publisher's efforts. If you want your project to succeed, YOU must become its major marketer and promoter. It's your job to contact bookstores, newspapers, and magazines, while organizing book signings, interviews, etc.
The entrepreneurial process is exciting and ultimately rewarding. Do it because you love to do it and you'll reap the financial benefits as a result.