Make the goal concrete
An early product discussion should turn broad ambitions into specific outcomes. Describe the user, the task they need to complete, and the improvement you hope to make. This creates a useful reference for later decisions.
Prototype the difficult moments
Use sketches or interactive prototypes to explore the flows with the most uncertainty. Ask prospective users to work through a realistic task. Observe where they hesitate, rather than only asking whether they like the design.
Agree on what comes first
Separate essential launch features from ideas that can wait. Define acceptance criteria together so designers, developers, and stakeholders share the same understanding of a finished feature.