The "To Keep Up" Wiki

(These from Trip Advisor with smi additions)

• Pack light to travel light. If you can manage with a carry-on, do it. Try taking half of the things you need and twice the money. You can make buying a few new items a fun part of the adventure.
• Bag it. Kitchen sandwich bags can be used to hold your accessories, vacuum pack bags can be space savers, and trash bags have multiple uses (laundry bag, shoe covers). Use bags to hold clothing (e.g., ziplocks and shopping bags, put all shirts in a bag, slacks in another, this way they slide around rather than forming creases.)
• Create compartments. Two words: packing cube. If you are visiting more than one city during your trip, packing cubes will keep your suitcase organized and save you from having to pack and unpack.
• Bring a multi-socket extension cord. Although newer hotels have USB ports in rooms, it’s best to have an extra outlet to charge all of your electronics at once. Also bring along an electric extension cord with 3 plugs, you'll need them.
• Pack a sleep mask and ear plugs. These can come in handy on a plane, train or in your hotel room.
• Share your packing space. Traveling as a couple? Split your clothes between two suitcases on the off chance one of them gets lost during the flight.
• Make photocopies before leaving home. If you’re traveling out of the country, make two photocopies of your passport. Use your smartphone to take pictures of your car in the airport’s parking garage and do the same for your luggage and its contents in case it gets lost.

From https://lifehacker.com/how-to-avoid-getting-the-flu-on-an-airplane-1822265077

• Pick a window seat. (else get germs from all walking down the aisles.
• Wait to board. (Avoid large, tightly packed together groups.)
• Stay Hydrated.
• Turn on overhead vent. (moves germs in your vicinity away from you.)
• Wipe everything down.

You can get early access to the plane by saying you have a peanut allergy and need time to wipe down the seat area.

Very unlikely it'll happen, but just in case.
How to survive a plane crash
In brief:

• Sit in the back of the plane. Within 5 rows of an exit door. Count rows to the exit.
• Wear cotton and wool. Tie-on shoes, long pants/jeans.
• Wet a hankerchief, put over your face, is temporary breathing mask
• Be wary within: 3 mins of takeoff, and 8 mins before landing. No sleeping or music; wear your shoes.
• Crash imminent: tighten seatbelt; cross hands on seat in front, rest head on hands (prevents whiplash & head injuries), wet hankerchief.
• After crash, get out! Get away from the plane!

Youtube video
In short:

• Under the insert in your gym shoes
• Inside an empty dental floss container
• rolled up in a partially used toothpaste tube
• Inside a deck of cards (remove inside of 3-4 cards)
• In a chapstick
• rolled around the ink in a ball point pen

You're in a hotel or a room somewhere and you want a cheap way to securely keep the door closed so even those with a key can't get in. Door lock out of a dinner fork
Commercial door lock on Amazon abt $22