Unless you're flying international Business Class or First Class, getting comfortable and 

what's in your will make or break your arrival day.

Herbal Tea Bags - make a cup of tea before you start your evening routine, then use the bags on your eyes for 10-15min.

Compression Socks - helps with swelling and cramping from long hours of sitting.

Outer layer - even trips to hot climates may mean cold flights. Pack/wear an oversized scarf, hoodie, shrug, cartigan, etc. Whatever it is, make sure it's comfortable and not too bulky. If I'm going to a place where I'll do a lot of swimming, I pack a turkish towel in my carryon (quick drying, light weight, doubles as a blanket).

Disinfectant Wipes - as soon as you get to your seat, wipe down everything and I mean everything.

Hand Sanitizer - keep it handy, use it often.

Hand Lotion - use a travel size, but fill it with your best stuff. Planes, constant hand washing, travel stress, all of this will dry out your skin. Keep it moisturized.

Lip Balm - again, travel will dry out your skin and no one wants chapped or flaky lips on their trip.

Fuzzy Socks

Toothbrush and Toothpaste or single-use brushes

Packet of Hot Sauce (optional): plane food isn't always the best and hot sauce can go a long way

Alieve PM (or similar) - this is my go-to because it's pain relief and a sleep aid.

Vitamins (especially for morning) - whatever you normally take, but double up on the Vitamin C and B (both are water solulable, help your immune system, hydration absorbtion, and naturally boost energy).

Eye mask, ear plugs, neck pillow - keep these together.

Pre-loaded audiobooks, podcasts, etc.

Chargers

Water bottle - helps keep you hydrated. fill it up right before you board and top it off when the attendants offer drinks.

Pocket fan - I can't tell you how many times me and my fan have been ogled with envy by boarding passangers on a hot plane. USB recargable is preferred.

Noise cancelling headphones - i prefer over-ear, but to each their own. Even if they're bluetooth, make sure they have an auxilary cord so you can use your own headphones to watch movies, etc.

Face and/or Body wipes - whenever you normally shower (evening/morning) is the best time to freshen up on the plane.

If you have back issues, get an inflatable seat cushion. Trust me.

For the ladies: 

Skincare Products - Get small or single-use containers for your daily skincare stuff. Do your night and morning routines on the plane. The routine and familiar products really help.

Panty Liners - wear at the start of your travel day and remove it when you freshen up. Like having a clean pair.

Makeup - don't try to access your full array of makeup on the plane. Instead, have a small pouch of essentials. I like to have mascara, a roll-on blush, and bronze drops (mix with my face lotion for a natural glow). Just a touch of self care will help you feel refreshed and ready.