Hi N.,
Are you traveling alone? My first trip with my daughter was a cross country flight (CA to ME) when she was 8-week-old all by myself. I will give you those suggestions, just in case you will also be solo! I've flown a lot since then and I feel confident in a few must dos...
1) Take a backpack as your carry on and nothing else. You will thank your lucky stars to have your hands free. Don't over pack much for yourself, but only items for the baby. Must haves: Change of outfit and blanket.
2) Check your airline website to check about bringing liquids/powder if you are bottle feeding. I recommend nursing or giving him a bottle at take off and landing to soothe ear pressure. The only time my daughter ever cried was when she did not nurse.
3) Through security, you will have to remove his shoes, your shoes and pass all bags through scanner. You also will have to fold down stroller/travel system(car seat & stroller combo) to go through scanner--all while holding your baby!!! Quite a feat to do alone.! I have always taken our stroller/travel system. It is a wonderful way to give your arms a break before and after the plane and allow you to use the restroom at the airport!! So... just be prepared!!
4) You will take your stroller/travel system all the way to the gate and get a ticket. Once you get to the door of the plane, you will take the baby out of the stroller and fold the stroller up before boarding. It will be waiting for you when you arrive as you leave the plane. (If you bought a 2nd tix for baby, then you will also take your car seat onto the plane to use.)
5) CAR SEAT! If you do not have a travel system, then you will also have to check in your car seat as luggage. (I always put my in a plastic bag for protection.) You will need it when you get picked up from the airport.
Okay...that's the basics. Good luck! Please e-mail me with any questions! D.