Get tickets to The Late Show with David Letterman. You can obtain tickets by going to the show's website. Unfortunately, if you have a visit planned to New York already, you might not be able to get tickets for a specific time or date. The next best thing to do, is to try and score tickets once you're in New York City. The show tapes at the Ed Sullivan Theatre, which is on Broadway between 53rd and 54th. The show tapes daily. Hours before the taping, interns from the show scout the Times Square area for possible last minute audience members.
Get to the theater early for your tickets. The tapings start every day at 5:00 pm, but you will need to check in at 3:00 pm. Get there by 2:45 pm to make sure that you're on time.
Be happy. It may sound odd, but once you are in the lobby of the theater checking in, present yourself as a very happy, well-adjusted tourist. If someone approaches you and asks if you're excited to see the show, or where you are from, give them an exuberant (but not over the top) response. The intern will most likely nod, and put a sticker on the back of your check in card. This indicates to the audience coordinators that you are to be seated on the floor and up front. You will be told to stand in a special line when it comes time to load in the audience.
Get to the theater early for your seating. You will be told to report back to the theater by 4:30 pm to be seated. Be there at 4:00 pm. You will stand in line longer, but you will be the very first one in line; increasing your chances for a front row seat.