Keep in mind that Liam was two months old when we flew, so these tips are for an infant around the same age. We'll be flying again with him right after he turns one, and that'll be a whoollle new ballgame!
1. Nurse (or bottle feed, or at least give a paci) during takeoff and landing to minimize any ear pain for baby.
2. Bring enough diapers! Should go without saying, but two hours into one of our six-hour flights, the flight attendant walked up to us and asked if we had any to lend to someone who had run out. Like, completely run out, with four hours left! (We did have plenty extra, but not even close to the right size, his son was a year old!) I don't know if they ever found the man any.
We packed about one for each hour of our trip. About 15 hours total, so I packed 15. Obviously much less if your trip is shorter or your child is older.
3. Don't bring diapers for the entire trip, just bring enough for the plane ride. Buy more when you get there. They have stores, I promise.
4. Bring enough wipes! (Obvi) I packed one of those travel refill packs, and that was plenty for our whole trip there.
5. Bring your own changing pad if you have one. (Maybe even get one for the occasion). I made a little fold up one myself using this tutorial that I carry with us everywhere. Sometimes it was really annoying to get up and wait in line at the lav on the plane to change a crying baby. It helped to have our own changing pad so that we could change him anywhere. (I even use it on the stations in the bathrooms because...well...ew!) Skip Hop also makes this cute one, and a lot of diaper bags come with one. Bring it!!!
6. To completely contradict my last several statements...pack light! As much as possible, that is. It's hard, I know, to pack lightly with an infant in tow. But assess your goods and ask yourself what you really need. I took my diaper bag and a small rolling carry-on to actually bring on the plane. Most of our 'extra' stuff-- extra diapers, wipes, blankets, & outfits--was in the rolling suitcase. Put the things you'll need easy access to on top of your diaper bag or in an exterior pocket--i.e., your id, boarding passes, a couple diapers, paci. Thankfully we didn't really need toys for Liam at that age, but we took one or two small ones just in case. (I don't have any fancy schmancy diaper bag. I just got one for 20$ from TJMaxx that has lots & lots of pockets & zippers!)
7. If you're breastfeeding--Breastfeed! Don't bring bottles of pumped milk. I loved the fact that I was exclusively breastfeeding when we flew. I didn't need any bottles, formula, a cooler, etc. If you need to bring a pump for your final destination, put it in your checked bag. If you are bottle feeding, bring only what you'll need for the flight, and put everything else in the checked bag as well. Don't forget your nursing cover if you typically use one!
8. Boppy? We had some people recommend bringing our boppy to put around our laps and let Liam sleep on it. We decided against it, for me it was just one more thing I didn't want to have to carry. We did fine having him sleep in our arms. (this might be tougher if you are flying alone without help, or if your child is bigger). You decide what's best for you.
9. Call ahead and see if the airline offers a bassinet. Ours didn't :( But some do! If you call right when you book your flight, chances are they might be able to get you seats in a front row (extra space!) with a bassinet free of charge. This really helps especially if you are not paying for a ticket for your infant (we definitely didn't).
10. We brought both our carseat and stroller, along with the carseat base. (Keith figured out a way to puzzle-piece the base into the stroller, with the carseat attached to it, but if you can't do this with yours, I definitely wouldn't bother bringing it. It will be a total pain, and just another thing to carry). You will be able to gate check both your carseat and stroller for free, and it really helps to not have to carry your baby all the way through the airport, especially if you're traveling alone.
11. A carrier won't hurt, either. We brought our Bjorn. Once we actually got to our gate, Keith got the stroller and carseat ready to check and we needed to hold Liam. I was so thankful we had it. We stood in line to board for 30 minutes a few times, and that made it so much easier.
12. Fly a lot? Think about getting gate check bags for your carseat and stroller, especially if they're nice enough that you don't want them scuffed up. Ours got some very noticeable scuffs. The bags are inexpensive (about 12$ each) but I didn't want spend that since we fly maybe once a year. You could also do a big trash bag, or buy those really big, industrial ziplocks like we did.
13. Dress for the airport! What I mean is...don't have a million pieces of jewelry, shoes that are a pain to take off, tons of bobby pins in your hair, etc. Getting through security with all your crap AND your baby in tow is already pain enough. You definitely don't want to hold up the line even more while you de-bling.
14. GET COFFEE, take a deep breath, smile a lot, try not to kill your spouse (you're in this together!) and enjoy all the attention