To get the most out of this book
You should already have an understanding of concepts such as APIs, file exchanges, databases, and cloud software models. You should also understand high-level concepts in the business-to-consumer (B2C) domain, including customers, products, orders, marketing journeys, customer service cases, and order management. This book is a roadmap with links to a huge and ever-evolving set of Salesforce resources. You should get into the habit of using the links, bookmarking things, and reading further on your own..
While reading this book, it's helpful if you re-work the examples in a context that's meaningful to you. Think about your own organization or a client that you're working with. How is your situation similar or different? How would that impact your architectural decisions? What might you do differently and what questions would you ask to understand the situation?
This book is intended to be a roadmap to a way of thinking about architecture. It's a snapshot of the features and functionality available in a variety of software products at a point in time. That stuff will change, but the overall approach does not. Ask the right questions, figure out what tools you need and how they will work together, document your solution, and iterate.
Do not expect to use this book as a shortcut to pass the exam. There's no substitute for learning the materials and understanding how to apply them in various situations. Focus on the process, experiment, take your time, and only when you've truly locked in the information should you move on to certification.