Leave the high heels at home
(Why do ads always show women wearing high heels on planes?) and opt for a clean, trendy pair of sneakers, or a pair of boots/booties.
Loose-fitting jeans and relaxed-fit jeans should be fine, but even beyond reasons of style, a pair of really tight skinny jeans simply isn't going to be the right choice for a long flight.
For the base layer on the top, it's a good idea to go with an easy t-shirt or long-sleeved top for a long plane ride. As we discussed, a matching set works well too.
Just a t-shirt is not going to be warm enough on a long flight, particularly not if the flight is overnight. Include a cardigan, lightweight jacket, or sweatshirt (no logos, please) to add style and warmth.
It gets chilly over the Atlantic Ocean in the middle of the night! I'd include one extra layer to use as a scarf/wrap/blanket during your travels. You'll also look chic AF.
Throw your travel pillow, eye mask, phone, headphones, water bottle, book, and any other
in-flight essentials into your tote, slap it on top of your carry-on bag, and you're on your way!