How To Handle a Panel of Interviewers During a Job Interview
The best way is to handle a panel of interviewers is to take them on one at a time. The board or panel is not one entity, but several ...

Board or panel interviews are usually rather formal and organized, using a standard set of questions for all applicants. This type of interview is typically used in academia, government or for high-level executives but can be used for any other type of position in any company.
Another multiple-type interview is the team or "good cop/bad cop" interview. The team is usually made up of two interviewers, one who asks the questions and one who takes notes. The two typically trade roles, which can be confusing if they have different styles. In fact, one person may be kind and gentle and the other more harsh or pushy. Just remember, these inquisitors are working together toward the same end. Treat them equally, not favoring one over the other.
Regardless of the type of interview, the best advice is to prepare and practice beforehand. When you have your script written and rehearsed your answers, you will feel prepared and more confident no matter how many people you have to face.
A good tip is to try to shake hands with each member of the panel before and/or after the interview if at all logistically possible.
Lastly, remember to make sure you get each person's business card, hopefully at the beginning of the interview, so you can address each person by name. And, when you write your follow-up/thank you note/email you can address each person correctly. When responding to an individual, try to remember what he or she was particularly interested in when they asked questions or received your answer.
Remember each person has an agenda - it is up to you to zero in on that interest and make the most of it.