Writers' conferences can be an excellent opportunity to network and learn about the business of writing. But in order to get the most out of any conference, you must define your primary goal. Yes it has to be more specific than "be a successful writer". Think about what you are trying to accomplish and who can help you toward that goal.
Study the panel biographies and develop a short list of relevant questions. Keep your questions brief. While a panel member may have a wealth of industry knowledge, she does not have the time to tell you everything she knows about the business.
On the other hand don't be so focused on your mission that you lose sight of potential opportunities. Even if you are intent on the traditional publishing route, it might not hurt to strike up a conversation with an indie romance author who happens to be on the USA Today's best seller list.