Custom travel-aid-kit. The things you don't think you will need.
It's always the simple household products that are the hardest to find when you really need them.
Needle and thread
On my first trip to a foreign country with my data already used up and no Wi-Fi in site, I couldn't translate the simple English words: needle and thread. Finally after a lot of abstract hand motions, somehow the shop owner in Uruguay understood what I needed. Don't be like me. It takes up little space and weighs nearly nothing and there hasn't been a trip so far where I didn't need it.
I can't even count how many times I've used a safety pin to fix a broken shoe strap or strap on a dress; a mishap that could take up a whole free day (having to go back to accommodation to change or pay to buy new clothing) was easily fixed just by having these pinned on the inside of my purse!
Again having this small thing on me saved my whole day from being ruined when i was on a walking tour in a bustling city and my boot decided to start falling apart! I literally just super glued it and carried on walking. It was a quick fix but it last the rest of the day.
Prescription for glasses/contacts
You would be surprised at how easy, fast, and cheap it can be to get prescription eye-wear abroad! The first time I needed to use my prescription was when my original glasses broke in half in Santiago, Chile. It was $40 USD and took 2 hours (on the same day!) to get a brand new pair of glasses! Try to beat that in the U.S.! Now whenever I'm in an affordable country I try to get a new set of frames. My latest pair came from Romania and were about $60 USD and again took only a few hours.
I bring about 2 boxes of each. I take everything out of the box of course but its cotton so it weighs next to nothing and can be squished in your suitcase. In some countries they only import the Tampax brand so its absurdly expensive to buy or sometimes it simply difficult to find feminine products or if you just have a favorite kind that works for your body, stock up and forget about it. Every women knows what its like to have the rush to the pharmacy to pick up overpriced cotton for the unexpected crime scene on the first day of her period, skip that and have it ready. Better yet, invest in a menstrual cup! Save money and the planet.
Enough said really. I's not the cheapest tool in your first aid kit but when you need it you'll be so grateful you bought it; and if you're from the U.S. like I am, you may want to consider stocking up anyway; because of the current political climate we may not have access to Emergency Contraception in the near future.
Small pack of tissues
Think squat toilets, allergies, someone coughs on you on a bus, the possibilities where a Kleenex can come in handy are endless.
Or any small container for sim cards and memory cards. They are such tiny things that are easily lost. You don't want to have to pay for another sim card when you come back home or lose all of your hard-won travel photos.
Rubber bands and zip-locks
After a few weeks or months you're going to find yourself doing odd things to save money here in there. Don't judge me because I once carried a bag of open coffee wrapped with a hairband through 3 countries before I finally found accommodation that actually had a coffee maker.
A portable fan
I actually used to think this was silly until I took an 5-hour bus ride in summer in Eastern Europe WITH NO AIR CONDITIONING. They are small, fold-able and rechargeable. I got mine from Flying Tiger Copenhagen and there are plenty on Amazon.
Portable phone charger
This one is self explanatory, you can stay charged on long flights, train rides, or just a day walking through the city. Just make sure you remember to charge the charger! Also bring one or two extra charging cables, they always break and may be way over priced in some countries you visit (I'm looking at you, Argentina).
Pack one or two of these babies and thank me later. These have saved me when I needed to strap my backpack to myself on a sketchy bus and for times when I needed strap additional things on the outside of my baggage, they are just so handy.
I use the Shandali travel towel for after showers or swimming and a small one for wiping down my laptop screen and other electronics.
For your luggage or storage lockers in hostels. If you don't have one with the you, hostels do often sell them but are overpriced.
The possibilities are endless! I've used peppermint oil for a sour stomach, tea tree oil for a cut or acne, lavender oil for a headache...they come in small bottles and you only need a little at a time for an impact. I always carry a few with my on long-term trips.
If you only take one thing with you from this list let it be travel insurance. It's important and if you travel long enough you will need it. I always use worldnomads.com but there are a plethora of options based on your home country, duration of your trip and destination and it is pretty affordable!
All of these items are pretty small, lightweight, and will make your life on the road