I used to do a regular 15h flight (MEL-LAX or LAX-MEL, I forget which was the longer one). I'd add: Get on board tired. Stay up late a few nights before you

I used to do a regular 15h flight (MEL-LAX or LAX-MEL, I forget which was the longer one). I'd add: Get on board tired. Stay up late a few nights before you leave, get up early, do a bunch of exercise, whatever it takes. Be ready to sleep. Book a window seat. You've got a decent chance of having only two people in the 3 seats for a start, which means extra leg room, and a blanket/pillow/headphones/etc dumping area on the spare seat. But most importantly, you don't get woken up when someone else needs to get up. The downside is you get to be the person disturbing the others, but ... that's better than being disturbed. Follow the pattern of the flight. There'll be a "night" portion of the flight, when it's dark and you don't get fed. That's the best time to sleep, so take advantage of it. Wear a hoodie. And get a pillow and a blanket. If you're on an airline that doesn't do them, consider bringing your own. You will likely need the blanket at night, because the plane will be cold, especially in the window seat. Wear an eye mask. Yes, it's dorky, but so what? It really cuts out the disturbance from the person in front with their reading light or video on all "night". Wear noise-cancelling earbuds with nothing playing to sleep. I find the background roar of the engines makes it difficult to sleep well, but the noise-cancelling drops it to a level that's heaps better. Get up and walk around when you can. You can do a decent lap around the economy section of a B747/A380. Flex your ankles as you walk, bouncing up and down. Do some stretching down near the rear escape slide doors. You'll still get swollen feet and ankles, but nowhere near as bad. Bring a book. It doesn't need working WiFi, battery, etc. If you ever get a seat with a broken entertainment system, you'll appreciate having the fallback once your phone battery is dead, laptop is drained, and the in-flight magazine is read cover to cover. Don't watch the map. It'll just feel like it takes longer. After you've had the final meal, you've got about 2h left. Final descent takes about 30 mins of that, so you've only got about 90 minutes of frustration between finishing the meal and making actual tangible progress towards your destination. The remainder of the flight is an alternative universe, outside of time and space. Disconnect, and just go with it. Otherwise you'll drive yourself mad.