Rather than focusing on a single source of income the lesson is to develop several. This covers you during seasonal slumps, tough times and boredom (you can switch off from business to business or client to client). It also helps you spread the risk around.
The key is to build your businesses that they support each other. You sell the same thing to different markets or different things to the same market. Publicity from one promotes another. When a customer buys something from you, they’re more likely to buy more of your products.
Build one venture at a time, get it up and running and then move on. I modeled this myself with books, online magazines/blogs about storytelling, seminars about storytelling, inspiration tours in storytelling, an annual storytelling conference, storytelling for coaches, a storytelling company for startups. When each new business supports the other, it works very well. When i get tired of being on the road doing seminars, i can switch gears and stay home and write.
One way to avoid getting too fragmented with this approach is to delegate for different ventures. Work together with a specialist to take care of conference details, work together with a graphic designer/publisher for the books,. You get the idea.