When designing a GraphQL schema, it's essential to know your domain well, including your application's UI and user behavior. A graph represents this data as a collection of objects and relationships between them, helping to visualize the structure and relationships of the data. By mapping out this graph before building the schema, developers can create an efficient and useful schema that mirrors their graph. The schema should also be designed for specific use cases, accommodating client needs without sacrificing conciseness or genericity. Finally, using specific and descriptive naming conventions can help clarify code and make it more maintainable over time. By following these principles, developers can build flexible and evolvable schemas that meet the needs of their application and users.