This document discusses the operational changes made by TravelBird to transition from a static daily email selection model to a personalized, portfolio-based model using machine learning and data science. It describes four main challenges: 1) defining personalization, 2) connecting operations to analytics, 3) capturing expert perspectives, and 4) balancing automated and hand-picked selections. For each challenge, it outlines the approaches taken, such as prioritizing quick wins like sort order testing before complex changes, using a real customer example to explain concepts, and giving experts tools to respond to current events. The key lessons are to communicate across teams, understand different perspectives, and find the right balance of automated and human input.