We flew with our son the first time when he was just over 2 months old. At the time he was still on bottles, so that took care of the sucking (chewing gum) that helps with the ears. Bring along a container of Cheerios or some other snack that he can chomp on to help the ears.
We flew from Houston to LA, with change of planes in Dallas. As we boarded the plane in Houston I gave him a small dose of baby Tylenol just to help keep him calm. I didn't want to be the mom with the screaming baby. It worked like a charm, maybe a little too good. He fell asleep before the plane ever took off and slept the whole time. Same thing on the connecting flight. I don't remember giving him another dose, but he slept or sat and watched the movie playing (without headphones). He also had a small bag of his toys and books to play with too.
He's 6 now and is a wonderful flyer. No more doses of Tylenol, but he usually falls asleep before or just as plane takes off and sleeps most of the flight.
Good luck and just remember to stay calm yourself. They can sense when you get uptight.