(I'm relatively new at e-publishing and don't have a huge portfolio. But here are my thoughts, for what they are worth.)
So, if you're wanting to get started in e-publishing, how do you get an idea on what to write about?
Harlan Ellison reportedly said the following when asked the the question "Where do you get your ideas?":
"A post office box in Schenectady. You send in two dollars and a self-addressed stamped envelope and they send you back an idea." (Barry B. Longyear, in his book It Came from Schenectady)
If you're considering writing a non-fiction book, on what are you the world expert? What are you really passionate about?
What do you think people need to know? When you look at the books available on the subject, what is the perspective that's missing that you can provide?
What unique personal experiences can you draw on? When you talk to people, what stories do you tell about your life or the lives of the people around you?
Fantasy and Science Fiction:
I cannot pick up an issue of the National Geographic without getting some new perspective on the world we live in. It may be a different source that feeds your creative process, but exposing yourself to new ideas is a must.
My wife and I have five children. If you spend much time around children, you'll discover they have a wealth of ideas. Occasionally, you'll find you can tell them things in a story they wouldn't sit and listen to if you tried to tell them outright.
Christian books often begin with a message. Our book, Broken Toys: China's Song, has a fairly simple message: God is in the business of healing broken hearts. Don't be afraid to pray for guidance when looking for an idea.
Value your ideas. When you have an idea, write it down even if you don't have time to write more than a sentence about it. I've been looking through some of my "Idea Notebooks" recently and it was like running across an old friend.
So, when you decide to put pen to paper, where do you get your ideas?
If anyone has that PO Box in Schenectady, I'm listening...