A question I'm often asked is where do you get your ideas? My answer is everywhere and ideas are out there. But not all ideas can be translated into works of fiction. I have a whole stack of ideas that haven't gone anywhere and probably won't. Another author could take one of them and fly with it.
Let's look at the idea that came from something that's happened to you. How to turn this into a story. I had a neighbor who was not a nice person and I wanted to kill her after some of the things she did. This idea evolved over several years and she turned into a young woman with no conscience who moved into a neighborhood and who attempted to destroy a number of lives including the heroine of the cozy mystery's family and friends. How did the evolution take place. By asking that question, what if. This was followed by another question, how about. Finally I had to remove the personal feelings and cast them into fictional ones.
The idea needs to be removed from the personal when trying to turn it into a book.
Another way ideas arrive is by just wishing something happened to ourselves. What if I won the lottery? What if I was a kick-ass heroine? From there the idea is taken from the factual to the fictional. The heroine or hero becomes your fictional alter ego. Sounds like fun.
Something we read or hear on the news is another jump start for a story. Again, the questions what if and how about come into play.Reading books, magazines, and well, maybe not cereal boxes, can raise ideas. Talking to friends may trigger ideas. It's getting the ideas from that stage to the book where asking yourself. What about this idea stimulates me? What if this could really happen? How about twisting the idea? What kind of characters do I need to design.
When the idea comes to you write it down. There are times when I forget to do this and then the idea is lost. I use scraps of papers, note books and sometimes index cards. Having ideas is fun and remember not all of them will work for you and the ones who do have to be taken from the factual to the fictional.