Choose the discovery moment
Start with a specific placement such as a product detail module or a next-read feed. Define the user action that would make that placement useful before choosing an evaluation metric.
Establish a baseline
A static popularity list, an existing rules system, or the current ranking can serve as a comparison. Offline evaluation can help screen strategies, while controlled online experiments test behavior in the actual product.
Keep guardrails in view
Clicks alone do not explain relevance. Consider the measures appropriate to your use case: engagement, conversion, coverage, diversity, and availability. Check segments as well as aggregate outcomes.
Close the feedback loop
Capture events consistently and connect them to the recommendation placement. Review data quality and missing signals before drawing conclusions. Refine the ranking strategy against the original objective.