I won't go over every flight tip, since there are tons of articles out there on that, but here are some basics that helped traveling with a toddler work more smoothly:
-Check the car seat at the ticket counter, and bring your own bag for it. We have an inexpensive red Gate Check bag that works great. Its torn from just 2 flights, which means the seats really take a beating so its a good thing we brought our own bag. Airlines are supposed to have them but sometimes are out.
-Husband and I were traveling together, so I packed her items in a cross body diaper bag. I included my wallet/ID in her bag. Husband wore a back pack with the rest of our items. More hands = better
-She doesn't use a stroller much, but to make security and gate changing easier, we brought an umbrella stroller. Bonus, she loves to push it around and it was a great time killer. Check your stroller when you board the plane, we've never brought a bag for it and never had it damaged.
-Pack lots of snacks - I used an Itzy Ritzy lunch box to pack a whole sand which and 3 different snacks. I don't know if its boredom, but she eats a ton when we travel. She thought having her own lunch box was pretty neat.
-Dress toddlers in easy to remove clothes. Diaper changes in the plane bathroom suck. Make sure they are wearing something that makes changing easier.
-I always read to pack lots of little toys from the Dollar Store. H really isn't that into toys, and I find that creating games out of stuff in the seat/on the plane works fine. Cups, napkins, armrests, tray tables, all provide entertainment. Get creative.
-The one thing we did pack that got her attention the most was a sticker book. I peeled the stickers off, she stuck them on the pages. I asked her to name things on the page. We sang songs about them. Whatever it takes. Best $5 from Target ever. Got it in the school supply section.
-We packed the ipad and a portable DVD players (I'm not smart enough to put movies on the ipad, I kind of hate technology). Both were barely used, but she did love the Wheels on the Bus app and the Tozzle app.
I also tried to plan our flight times around nap time, and it worked for the return flight home. I brought her blanket and 2 stuffed animals. They take up space but she LOVES them and I knew they would help her calm down if needed. We also bought her her own seat, which they don't have to have until age 2, but it was totally worth it. Made the flight much less stressful and she loved sitting in her own big girl seat all buckled in like Mommy and Daddy!