Preparing for a Google system design interview requires a strategic and comprehensive approach, given the company's emphasis on designing scalable, efficient, and reliable systems. Here's a plan to get you ready:

Understand What Google Looks For:

1. Scalable System Design: Google often deals with systems that operate at an enormous scale. Show that you can design systems that scale both vertically and horizontally.

2. Problem-Solving Skills: Demonstrate a strong ability to break down complex problems and present clear, efficient solutions.

3. Practical Knowledge: Be ready to apply theoretical knowledge to real-world scenarios.

4. Communication: Clearly articulate your thought process, decisions, and trade-offs.

Core Preparation Strategy:

1. Study the Basics:

   • Deep dive into distributed systems, databases (SQL & NoSQL), load balancing, caching, network protocols, API design, microservices, etc.
   • Understand Google-specific technologies like Bigtable, Spanner, or technologies they use frequently.

2. Design Fundamentals:

   • Review basic architectural patterns and principles.
   • Understand concepts like CAP theorem, consistency patterns, and data replication strategies.

3. Practice System Design Questions:

   • Regularly work on mock system design problems. Focus on questions that are commonly asked in Google interviews, like designing a web crawler, building a file-sharing system, or scaling a social network.
   • Use resources like “Cracking the Coding Interview” by Gayle Laakmann McDowell and “System Design Interview – An Insider's Guide” by Alex Xu.

4. Mock Interviews:

   • Practice with mock interviews. Platforms like Pramp, Interviewing.io, or LeetCode can provide a realistic interview experience.
   • If possible, get feedback from peers or mentors who have experience with system design interviews.

5. Learn from Real-World Systems:

   • Study existing architectures of large-scale systems, especially those built by Google (like YouTube, Gmail, or Google Search).
   • Google's engineering blogs can provide insights into their approach to system design.

6. Review Your Past Work:

   • Reflect on your own experiences. Be prepared to discuss past projects or systems you’ve worked on, especially situations where you had to make significant design decisions.

7. Stay Updated:

   • Keep up with the latest trends in system design, as Google values innovative and up-to-date solutions.

A Week Before the Interview:

• Review and Summarize: Go over your notes and summaries to reinforce your understanding.
• Focus on Weak Areas: Spend extra time on topics where you feel less confident.
• Relax and Rest: Make sure to get enough rest before the interview. A clear, rested mind is crucial for success.

On the Interview Day:

• Clarify Requirements: Don’t hesitate to ask questions to understand the scope and constraints of the problem.
• Think Aloud: Explain your thought process as you structure your solution.
• Engage with the Interviewer: Treat it as a collaborative discussion rather than a test.

Remember, Google is looking for candidates who can think critically about complex problems, articulate their thoughts clearly, and design effective, scalable solutions.

Ref: Google interview guide.