The best entry into e-book publishing is to identify your own expertise . You share your interests with hundreds of thousands, possibly millions of people, many of whom will be delighted to pay you for your knowledge, so that they can enhance their own abilities. The difficulty we all experience is identifying what other people want. We simply don't believe that our knowledge can be sold to others. And, of course, almost all of us know or do something which is so much part of our lives that we don't even recognize it as a skill .
Cooking is an excellent example.
There are millions of American women who would 'kill' for grandmother's recipe for making the perfect dessert. Tell people what mistakes to avoid when buying a home. Tell people how to save taxes. Tell people how to save money when they next buy a car. The list goes on.