Do your research. Who will be in the audience? How does this panel fit into the broader objective at the meeting and how does it complement or vary from other panels?
Define objectives, what does the audience want? What do you want them to walk away with?
Give strategic thought to who will be on the panel. Shoot for diversity in all areas – gender, subject matter expertise, issue perspective, age, etc.
Get a brief bio from each panelist. Focus on making sure you can pronounce their name correctly and that you get their title correct.