Panels are a low form of public speaking.  It's a lazy, cheap way for a conference planner to fill an hour or 90 minutes.  But you get what you pay for in this as in other things.  Rarely does a panel provide memorable content. 

The success or failure of a panel in the end all depends on the moderator.  A good moderator can tie the ideas together, challenge people, and keep the conversation going.  I've probably seen that happen twice in my 20 years of conference-going.  Usually a panel is a depressing spectacle of speakers overrunning their time, repeating themselves, or rambling inexcusably because they haven’t prepared since ‘it wasn’t a real speech'.  There’s very little interaction between the panelists, the moderator just sits back and watches the train wreck, and the audience’s time is wasted.  

How can you improve upon this pitiful record?  Let’s imagine you’ve been invited to be on a panel.  Audiences always say they wish the one good person on the panel had been allowed to speak for the entire time.  So your goal is to be that one good person.  What are the secrets?

First, make it a little easier for the moderator by preparing a good introduction that provides some 'hooks' for the moderator to know what to ask you.  "Jim is well-known for his controversial opinions on the proper temperature of yak milk for optimal storage life."

Second, prepare a 10-minute speech that leaves out detail but hits one controversial point, and has the overall structure of a good, persuasive speech, just in 'lite' form.  Prepare questions and answers by deciding what you would like to be asked and then prep the answers so that no matter what the question, you get to put yourself forward in an interesting way and in a good light.  "I'm glad you asked me that question about little green men.  What I find, in my experience, is that it's not so much the specific case that matters as the general rule.  So, for example, when I'm thinking about the issue of how IT can help the business......" OK, an extreme case, but you get the idea.

Third, if you want to overachieve, study the other panelists and their ideas in advance, and make friendly, polite comments when answering your questions that refer back to them.  "As Bill rightly says, it's not the bytes, it's the bits.  What I find, in my experience is that...."  or "Let's not forget Jane's point about the future of Oracle.  Just the other day, I was talking with President Obama about where IT was headed, and I told him...."

The other panelists will be so pleased that you mentioned their names that they won't care (too much) if you don't spend a lot of time on their ideas.  Just reference them and move on.   Even better, link your ideas and theirs in meaningful ways.  Your audience will deeply appreciate the help. 

Finally, if you really want to overachieve, call the other panelists in advance and interview them.  Ask them what they're going to say.  You'll find out a lot about their personalities, which will help you prepare for the spotlight hogs and the cranky, idiosyncratic nay-sayers.  And you can do the moderator’s work to an extent by linking the ideas together and drawing some conclusions for the whole.