Here is a carry on checklist that I like to use for my backpack or smaller bag that I take with me on the plane:

1. Some sort of technology [if you have it]: I always like to download movies or even music before the plane ride so that even when the wifi is off or you do not have any data in the air anymore, you can still enjoy a little bit of entertainment.
2. Snacks! It is always good to have a little granola bar or fruit snack fro on the plane and maybe something a little bigger for in between any flights so that you don’t have to purchase anything in the airports.
3. Chapstick and lotion. I have a firm believer in always having these with me in the airport and on planes because I always feel like flying drys out my skin. Maybe that is just me, but I have definitely heard for others that it is a good thing to have on hand as well.
4. A good book. I always take a book to read on the plane or in the airports to pass time. You never know when you’re phone will need a charge in the airport  and you’re left with nothing to do. Just whip out that book fro a little bit.
5. Headphones and chargers. Connecting to that last one it is always good to have a charger in case your phone or other devices are dying after a long day of traveling. They usually have quite a few charging stations within the airports. Also, headphones are good for watching those movies and listening to that downloaded music on your phone.
6. Hand sanitizer. This is always one of my essentials because you know that there are people flying all the time and you never know who was in your seat last so it is always a good idea to use it in between flights to keep away from getting sick.
7. Folder for tickets. This could also be a me thing but I love to bring a small folder or something to put my plane tickets into so thatI don’t lose them and then to keep them for a scrapbook or something of that sort.
8. Small wallet. A small wallet is always a good choice so that you can keep some cash on you and have your IDs readily available for security and check-in. Just a small one that slips into your bag easily will do, and one that you can access quickly.
9. Empty water bottle. This is the best tip I have learned over my traveling days and that is to bring an EMPTY water bottle to the airport. Prices fro stuff like this is getting pretty ridiculous and airports always have water fountains and even those water bottle fillers. If you just bring it and fill it up once you have passed security, you can take it with you on the planes and not have to pay for one once you get in.