Francesca Guiducci, who has years of experience with GraphQL at scale, shared her insights on designing a GraphQL schema during a NodeSF meetup. She emphasized the importance of involving others in the design process, especially those knowledgeable about the domain and data. She also stressed the need to start thinking in terms of graphs, rather than exposing methods or endpoints, and to carefully craft and nest data for better performance. Other key points include designing a schema that is easy to evolve, being intentional with nullability, implementing pagination, and addressing challenges such as versioning, performance, and testing. By following these guidelines, developers can create a robust and maintainable GraphQL schema that meets the needs of their application.