You’ve worked on a project for days, if not months. You spent countless hours sitting in meetings with the client to understand and refine what their needs are. You effectively are the expert in the problem placed before you by the client.
Why not act that way? When in a pitch, understand and believe that you are the expert. No one can know this brief better than you; no one can present your ideas better.
Half of creative is not the art, but the pitch… Learn both sides, and you’ll have mastered the art of the business, not just the craft.