Well, first you need to have a clear idea of the story and characters. Then outline the key plot points, character arcs, and the world-building details. This forms the basis of your comic book bible.
Writing a comic book bible involves a lot of planning. You have to decide on the theme and tone of the comic. Develop a comprehensive setting and list any recurring motifs or symbols. Also, sketch out potential subplots and how they relate to the main story. It's all about giving a solid framework for the comic to grow from.