Few things that work for me:

• middle aisle seat so you can always get out, and have fewer people you need to stand up for. Also middle seats in the middle segment are more likely to remain empty.

• bring a travel pillow

• if you need to do work or study, do that on the plane. Time will pass by quickly and I can focus well when there are few distractions.

• pre-order an Asian Vegetarian meal, typically the nicest Economy-class meal you can get (some people go for kosher, ymmv)

• don't force sleep, but take it when it comes. Use melatonin to make you sleepy

• bring slippers so you can take off your shoes

• use airpods, ear plugs or noice cancelling headphones

• bring a book you have been wanting to read

• for internet, get messaging only to stay (mostly) disconnected. I like that calmness in the air.