Most of us have arrived at the airport, only to realize that we forgot something. I once went on a trip to Kauai, and forgot my golf clubs!!! And golf shoes. I had to rent clubs, and buy another pair of golf shoes. Since that untimely event, I always use a list when I pack for a long trip.
After printing my boarding pass, I always place my passport in a clear plastic folder with the rest of my travel related documents. If you use the airline’s app, I would still print a boarding pass as a backup. And I always keep my Driver’s License (Real ID) in my wallet. And I have photos of each on my cell phone.
The online check in process serves several functions. One might be paying for your baggage, printing a bag tag, and even choosing or upgrading your seat. I always try to do this 24 hours before boarding. Always!
I always have the airline’s app on my phone, even if I don’t use it. I also agree to receive text messages regarding delays or cancellations. And another really important notice, gate changes.
Often overlooked is how to dress for the flight. Comfortable, yet tasteful is my suggestion. One item that should be banned, in my humble opinion, is flip flops. Why? Think about it, in a fire, flood, or making a run for it, flip flops are a real liability. And even in summer, a light sweater or jacket since the planes are often quite cold.
The proverbial refillable water bottle has become an important part of travel. But so are some snacks from home. Just a small bag of nuts, an energy bar, or cookies will help you get to the next meal. I hate paying outrageous prices for airport snacks that are both stale and unhealthy. Save some money and spend it on a nice meal at your destination.
Spring for TSA Pre-Check! The lines are shorter, and it only costs $85. And you generally leave your electronics inside your bag, keep your shoes on, and zip right through.
If you are unfamiliar with an airport, it pays to go online for an advance look, or use the map in the airline magazine. Some airports, like Dulles in DC, Denver, O’Hare in Chicago, Heathrow in London, LAX, SFO, and Hartsfield in Atlanta are configured in a confusing architectural nightmare at best.
Whether renting a car, using Uber or public transportation, I always look at my options online before landing. Signage, particularly in foreign airports, might not be as clear as airports here in the US. The worst of course, was in Russia.
If you have other suggestions, please share. Travel should be fun, free of hassles, and a memorable experience.
golfkat Travel Blog 
Yes I always download the airline app. and print boarding passes as a backup . And like you I always take my water bottle and snacks. But my plan is not take check in luggage. I take carry on luggage only. I have lost luggage many times.
I carry on like you on shorter trips. But Europe, Asia, and South America require more, at least for me. Plus I take lots of gifts, give clothing and shoes away, and return home either empty or full of purchases.