Building robust real-time React applications with Socket.IO requires you to follow several best practices. First, manage your socket connections carefully: always establish connections at the right lifecycle moments and clean up listeners and connections to prevent memory leaks or duplicate events. Second, use clear event naming conventions by adopting namespaced and descriptive event names, which helps prevent conflicts and makes your codebase easier to understand. Third, ensure reliable state synchronization between the server and React components by updating state only in response to relevant socket events and minimizing unnecessary re-renders. Finally, always consider security: validate and sanitize all incoming data, authenticate clients before allowing sensitive operations, and avoid exposing sensitive information over socket events. By applying these principles, you will create real-time features that are reliable, scalable, and secure.