One way to sell them is at local comic book conventions or flea markets. Set up an appealing booth with your items neatly displayed. Interact with potential buyers, share your enthusiasm for the graphic novels and comic books, and be knowledgeable about what you're selling.
Another option is to sell them to local comic book stores. However, they might offer you a lower price compared to selling directly to customers. Before approaching them, make sure your items are in good condition and are in demand titles. You can also try reaching out to collectors directly through social media groups dedicated to graphic novels and comic books collectors.
You can start by setting up an online store on platforms like Etsy or eBay. Take good photos of your graphic novels and comic books to attract customers. Write detailed descriptions including the condition, title, and any special features.