Keep asking “what if…” all throughout your story creation process. For example, what if your character did / did not do something…. What if that problem was different, then what?
Try and explore the things that can’t be easily seen in a drawing like thoughts and feelings, and other senses.
Tip: Don’t use an eraser at any point in your story creation process. Just cross out what you wish to edit out or start working on another sheet of paper. You should keep all sheets of paper together and don’t throw anything out until you have finished your story as final. You never know how one idea might develop and you may need to go back to refer to earlier versions as a continuous loop in a story creation process.