1. Portable Charging Bank

On every trip, I will bring a normal phone charger (extra-long USB cable and block). For longer flights, car rides, amusement parks, or any doubt of access to a power outlet, I will also bring a portable charging bank. I have a pretty large one that came with my Away suitcase, but also recommend this lighter Anker bank and an enormous one for camping that can be recharged via solar (similar one here).
2. Earplugs
I bring earplugs on every trip, and there is usually a pair in both my backpack and toiletry bag at all times. I have several family members and good friends who snore, plus you never know if there will be noise from the road, crying babies, or other people! The earplugs also come in handy on planes, trains, and other transport to block out noise at any time of day.
3. Snacks
I always travel with a heavy-duty granola bar (e.g., a full sized Clif bar) and empty water bottle to fill up at the airport. Okay, so the Clif bar is usually in my purse or backpack because I get really grumpy when hangry, but I’ll always have snacks in my bag for travel. This helps with any unexpected delays or if you don’t have time to pick up food. I like Clif bars because they are calorie dense for the size, and are pretty difficult to crush or crumble in your bag.
If my trip spans a mealtime, I’ll also bring a heftier snack like a sandwich or something easy to eat out of a plastic Ziploc bag like some pasta. I recommend something you would pack in a sack lunch that is simple and low in odor.
4. Contact Lens Cases
A great, inexpensive toiletry container is an empty contact lens case. I have several small 1-2oz plastic bottles for items like lotion or shampoo, but really struggled to find a smaller container for things like makeup (foundation) or fancier face lotions or serums. Contact lens cases are great for these smaller quantities and I have not had one leak either.
5. Waterproof Dry Bag for Phones
This one isn’t appropriate for every trip, but it’s inexpensive and has been a lifesaver on trips where your phone will get wet or dirty. I have taken this phone bag tubing or to the beach. Note that for tubing or rafting, you might want to also clip this to yourself with a small caribiner in case you flip over. I have also taken it on longer trips – in Thailand this came in handy during songkran water festival and surprisingly, an elephant preserve where we weren’t necessarily getting in water but were getting covered in mud and dirt!