As someone who travels 1-2 times per month for various reasons ranging from work to personal trips, I like to think I've mastered the "travel day" aesthetic and essentials.
First, there's your outfit. I really don't care where I'm traveling to, I always try to dress cozy. Planes are notoriously cold and I'm typically cold-natured, so you can usually find me in leggings, a t-shirt and a cozy oversized sweater. Another travel day tip is that I NEVER wear flip flops or flats when I'm traveling. There is literally nothing more disgusting than walking through security with bare feet. YUCK.
Next, there's your bag to consider. I always carry my Louis Vuitton Neverfull bag as my carry on. I make sure to stock it with a few of my travel day essential. I love to pack one sweet and one salty snack, my refillable water bottle, a book or my iPad, my baby blanket (yes I'm 5), my crossbody purse, chapstick, hand sanitizer and some headphones.
Most people try to load up their bag and it in turn becomes very uncomfortable and heavy to carry. I usually also carry on my smallest rolling suitcase, that way I don't have to worry about checking a bag.
The biggest thing to note is don't overpack! Before I traveled so frequently, I was constantly overpacking and all it did was cause myself back problems & more stress. I hope this short overview helps you to be prepared on your next trip.