Use this framework for system design:
Clarify requirements (- minutes)
- What are the core features?
- How many users? (approximate is fine)
- Read-heavy or write-heavy?
High-level design (- minutes)
- Draw main components: client, server, database
- Show how data flows between them
Deep dive (- minutes)
- Pick - components to discuss in detail
- Discuss tradeoffs for your choices
Address bottlenecks ( minutes)
- Where might the system fail under load?
- What would you improve with more time?
This framework shows structured thinking even if your knowledge is limited.