Not all those who wander are lost, but I certainly am!
I have to admit, gentle reader, a hesitated to name these items necessities if only for the fact that most aren’t that necessary. That said, these are small, scout-style improvements which will ensure nothing catches you by surprise during your trip. As a bonus these are all items which can help you, those who travel with you, or strangers in need of a hand.
#1. A small first-aid kit.
Notice the word small. If you’re heading somewhere remote like camping or hiking, or you’re going into an area that isn’t exactly tourist friendly, then by all means bring a med-kit. Otherwise, a little plastic bag with some a few pain pills, Polysporin, Benadryl, and Band-Aids will do. Think treating blisters, not bullet wounds, so something significantly less complex than the image below.

#2. A Red Bag.
For period-havers, you know what to do. For those without periods here’s what we need. Pack some pain pills, a few pads and some tampons (options are always nice), and some wet wipes. Pack more than you think you’ll need of each item; remember the girl code! Keep it discreet by packing the items in a little pouch or wrapping them in an opaque plastic bag. It’s always nice to have your friends’ and partners’ backs, and I guarantee they’ll appreciate the thoughtfulness.
#3. A plastic garbage bag.
If your water bottle spills, your sweater or coat gets so dirty or wet that it becomes unwearable, or you become ill, you’ll be glad to have a leak-proof bag on you.
#4. Hair elastics.
Anyone with long hair knows it’s a massive pain when you need one and don’t have one. Even if you’ve got short hair they can be used to secure locker keys to your persons, tie shirts to make them fit better, and send signs to your friends. Make sure they’re elastics meant for hair though, as plastic ones are an absolute nightmare to get out of long hair.

#5. A small knife.
No, not a switch blade, butterfly knives, or a buck knife. Those are too big and too illegal in certain countries. You’ll not be using this knife for self defense. What you’re looking for is just a fair sized pocket or swiss army knife. This is for cutting tags off new clothes you want to wear, getting into tough packages, or emergency modification of clothing like loose threads or frayed edges which are making you trip. There are plenty of other uses too, it’s just a useful little tool to have around. DO NOT PUT THIS IN YOUR CARRY ON IF YOU’RE FLYING. You’ll be forced to get rid of it by security.
With these items in your bag you’ll be a bit more prepared to face the little every day emergencies we all face. Wear a mask, wash your hands, and stay safe gentle reader.