A concept map can help plan out your research by getting all your ideas out of your head and on paper. Connecting different concepts together organizes your thoughts into groups of similar ideas so you can communicate your ideas as connected parts of a whole instead of a disconnected list.
Start by thinking of main characters, objects/symbols, and major events. How are they connected? Are there any overarching themes? What about the social, political, or economic context of the book or author? Could they be analyzed or interpreted differently depending on a literary theory* being applied?
*A literary theory is a school of thought or type of literary analysis. Some examples are: feminist theory, ecocriticism, and post-colonial theory.