Take scented dryer sheets in plastic bags. In a lot of countries, people still smoke. You can wipe down your clothes and hair and remove some of the smell. They can freshen a musty hotel room. If you are seated on a plane with someone who doesn't use deodorant and thinks showering is optional, it can distract you from the body odor. After you are out of sheets, you can put your dirty laundry in the bag.
Keep a couple of American dollar bills handy so you will have what you need to feed into the luggage cart system. After a big trip, you may need those carts.
Carry a half-full (or small) plastic bottle of water in your carry-on. I drink the water while waiting to go through security. I keep the bottle, which I later fill so I have a bottle ready for my journey from airport to hotel.
When you first enter your hotel room or stateroom, even before unpacking, find the in-room safe to deposit valuables. If there is no safe in-room, there may be one behind the lobby reception counter. Withdraw items only when needed and, of course, when checking out.