What are the key aspects to consider in a first meeting with the decision maker?

A new project is starting, 8 people are forming the board of decision-making. They have high expectations regarding the user experience - yet, they do not seem to have a strong experience with a process or user-research.

As the main responsible of the design process I want to make sure that they understand that user testing is absolutely mandatory and that there will be some iterations. On the other hand, I do not want to appear too blunt or to impose a methodology.

How should I behave on this first encounter? What should I be concerned about the most?