Your audience will feel that they have wasted their time if they don’t know why they are there. It is critical that you detail what you want from them. You need to present the rationale for whatever you are asking for, such as a budget, plan, schedule, a proposed team, their time commitment, etc.
This provides the audience with a concrete proposal, but it also builds confidence in you as a project manager.
Be prepared to provide more detail if asked.
Be specific about the timeframe for approval. If you can get signoff on the spot, get it. Otherwise, organise a follow-up meeting.