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.