Almost all nonfiction books have lists – because you need supporting factors for the main argument, hence, a list. The problem occurs when lists are too long and suggest too much work. For example:
50 Ways to Save Money sounds like a great idea for a book.
50 Qualities of a Great Leader doesn’t sound so great for a book.
Some lists promise abundance while others suggest labor—and that is the crucial difference. Many authors have ideas for lists but often don't realize that their book has to be approachable. If I think I have to do a whole stack of things to be effective or learn 25 new things to understand something, I am automatically turned off by the task. This is why "7 Habits..." sells even to this day. Seven is an approachable number—it is doable, a “comfortable” number that is still not too simplistic and can also be remembered (though science tells us that anything over four things slips our memory).
My personal opinion is that any list over ten items long is pushing it. Prune your list to the essentials and remember this: you don't have to write about everything, just the most important things.
Oh, and be sure to have a unifying concept or idea behind the list. Anyone and their mother can throw together a random list of qualities, processes, ideas, thoughts, etc. But with no core idea that holds them together (beyond just a generic descriptor like "contributing factors” or “strengths” or “qualities”), they are just that—a random list. And there's nothing memorable or compelling about a random list.
Crankily yours,
