If you've been struggling with a plot, or you're looking for ways to deepen an existing plot, try looking at how your protagonist's internal conflict is driving her external actions.
A lot of focus gets put on the core conflict of a novel—the main problem the protagonist has to solve to win—and for good reason. It's the whole point of the book. But sometimes, when we look too hard at the external problems, we miss out on opportunities to let the internal problems muck things up. This is especially true in a character-driven novel, since that inner journey is what's driving the entire book.
While you can’t plot with a character arc, you can use it to create your plot, because what a character has been through and fears, if what determines how they face their problems and make decisions.