The best advice and the worst advice we received about traveling with an infant.
BEST: Our Doctor told us to bring new toys with us instead of familiar ones so that Toby would be engaged instead of comforted on the plane. We almost didn't need all the toys we bought with us because once we got to the toy phone that's all he wanted, all he still wants actually.
WORST: A dear friend told us not to bother with a stroller. We liked the advice because we didn't feel like hauling it around. We ended up bringing one home with us from England and what a difference it made. Having a reclining stroller meant Toby got a nap in the airport on the way home whereas on the way there he was awake for 8 hours straight which made for a screaming fit while taking off.
BEST: Bring plenty of diapers, wipes etc but pack enough for one diaper change in a smaller bag that is easy to store in the seat pocket. Replenish after each change and you never have to worry about taking the big bag into the small bathroom on the plane.
WORST: Don't buy the extra seat, he'll sit in your lap just fine. Admittedly we couldn't really afford the third ticket but my what a difference the space would have made. Toby loved sitting in my chair and I think this would have been better than all the new toys we took with us. He also hated being in my lap for extended periods of time, very restrictive for an inquisitive little boy.