Every author has his own method of when and how to transform an idea into a book. All I can do is to describe my method. It usually starts with a general idea or theme for the book. The next step for me is to develop the ending. I would ask myself where or how I would want the book to end. I draft the ending in as much detail as I can at this point, knowing that some of the details will change.
The next step for me is to develop the main character. I develop the character to the point where he or she becomes a living person in my mind. The character is the guide throughout the story.
Next step is to develop a general outline for the book, using the main character as the focus for each section. Each major section in the outline specifies what I want to accomplish and which characters are involved. This provides me a timetable when I need to introduce new characters into the story. In The Mosquito Bites, Alex Gregory is my main character. Each section of the outline becomes a chapter in the book. The outline, however, is only a guide and can change as the story develops. But it is a good starting point. Sometimes I will remove entire sections in the outline, whereas other times I go in a new direction. The main purpose of the outline is to keep me on track, always keeping the ending in mind. It is like a map leading to the end, with many twists and turns to get there.
Author, The Mosquito Bites