Disinfectant wipes - I like the Herban Essentials ones in the lemon or lavender. I ask seatmates if they mind if I use it since it's scented. I offer one to them and thus far over many dozens of flights everyone's been fine. I have an alcohol wipe in my bag should anyone ever ask that I don't use the scented wipe. I wipe down the armrest, seatbelt latch, remote control for the TV if I'm going to use it, and the tray table as soon as I get to my seat. When I first started doing this I had mild concern that I looked a bit germophobic, but so many airlines are trying to shave off turnaround time that the planes are not well cleaned and usually the tray tables are quite disgustingly dirty. My seatmates usually take one for their own use.
I have tried many travel pillows and take overnight flights often. After a lot of trial and error, I bring the Igloo travel neck wrap now. It's not inflated but a memory foam type wrap that secures around your neck and supports your head better than any other pillow I've tried. They look a little crazy but it's better than a wrenched neck or a sleepless flight. It comes with other accessories - an eye mask, a lumbar cushion, and a storage sack that can also be used to support your arms. The storage sack is the only other thing I use other than the neck wrap. I have trouble with my arms falling asleep on long flights and the arm support helps. This is the igloo product: https://igloo4travel.com/
Also after trial and error, I use the Bucky 40 blinks eye mask, which is the most comfortable and blocks light the best. https://www.amazon.com/gp/product/B00M6NSLBE
I also bring single use eye drops, a packet of tissues, and lip balm.
Sometimes I bring an travel-sized evian mister (you can get them at sephora), but not always, as half the time I don't use it and it takes up precious space in my quart sized bag. I fly with carryon only and have optimized my cosmetics & toiletries.
I have noise canceling headphones which I wear for most of the flight but also bring a pair of ear plugs which I sometimes wear for longer flights or sleeping if the plane is fairly quiet.
I have several playlists of ambient sounds, 'music for sleeping', and ocean surf which I cue up when I am trying to sleep on a plane.
I bring a charged up kindle (paperwhite) and also at least one magazine or book in hardcopy.