While packing, remember.
You can have one quart sized zip bag of liquids and pills in your carryon bag.
Liquids must be in containers of 3 oz or smaller.
You can also have a bag of small liquids in your checked luggage.
Things you can’t live without or would be hard to replace should be in your carryon bag. Such as medicines or expensive or hard to find lotions. Things you could get anywhere, shampoo or deodorant, such like, can ride in your checked luggage. Still, use small bottles as they may leak in the unpressurized cargo bay on the plane. If they are not full containers, squeeze all the air out you can as this can keep them from expanding and leaking.
Pack at least one complete change of clothes in your carryon. That way if your luggage goes somewhere you don’t or you miss a connecting flight, you have something fresh to change into the next morning.
Also include in your carryon bag all the electronic accessories you will need. Chargers, e-readers, tablets, camera memory cards and cameras. If you can gather this all into one bag, even better. Especially all the little pieces and wires.
Always carry a second camera battery and more memory cards than you think you will need. It’s easy to get carried away shooting pictures in this digital age.
In your checked luggage, have one more change of clothes than days you will be gone. You never know. Things can get spilled on you or you could get caught in the rain.
Check the weather where you’re going and pack accordingly. Also include clothes for a change in the weather if you’re traveling in the spring or fall. Cold fronts can’t always be predicted accurately a week out.
Have an extra pair of shoes. You may need to switch it up every day or two for your feet’s sake.
Now, after having read all this, start your list making. Make several lists, and keep them with whatever they refer to. One list for carry on bag, one list for checked luggage, etc. refer to these lists often and mark things off when they ACTUALLY GO IN THE BAGS. Not just when you make a pile or buy something.
Last, and probably most important, print out ALL your documents. It doesn’t even hurt to have duplicates stashed in multiple places. If you can unfold a printed piece of paper and hand it over as proof, there’s a lot less argument if things don’t match up. If you’re using your phone app for a boarding pass, print it anyway. Technology does fail.