Choose a bag that is large enough to handle all the things you need to take, but small enough to fit the size requirements for carry on luggage at your airline. A soft sided bag is best, as it can serve as a pillow should you become stranded in an airport.
Put in two changes of underwear and one set of extra clothes. This is especially true if you are traveling overseas. These flights are very long and you may want to freshen up somewhere during your trip.
Add your daily toiletries. Things like toothbrush and small toothpaste, contact lens solution and case, facial care products, a small bottle of shampoo and lotion. All of these should be packed in plastic zip up storage bags in case of spills.
Pack a large water bottle. Airplane air tends to be dry and keeping well hydrated is important. Take advantage of water offered in flight and save yours for when you need it.
Add snacks to your bag. Never count on having time to stop for something to eat while traveling. Keep non-perishable food items in zipped bags. Crackers, raisins, nuts, granola bars and chocolate all travel well. Be sure to include a pack of wet wipes for quick washing up.
Carry medications. This includes insulin even though it involves a needle and may take you a little longer to get through security.
Take a sweater, sweatshirt, fluffy jacket or compact blanket for warmth. These things may or may not be available in transit, and you want to be prepared for temperature changes.
