System design interviews can be tricky. Focus on scalability, reliability, and maintainability. Candidates often overlook trade-offs. For example, eventually consistent systems can save you in performance but complicate user experience.

Don't just throw architecture diagrams at the interviewer. Talk through your thought process. Tools like AWS or GCP can come in handy, but knowing when to use them matters more than just familiarity. Real-world scenarios often involve unexpected challenges. Be ready to pivot your design based on constraints or feedback.