My two cents -

• Dress comfortably, wear khakis instead of jeans. Carry a jacket or a blanket
• Carry 1 mg of Melatonin, take it if you have a red-eye or a flight above 5 hours
• If you bum is getting sore, get a small pillow and sit on it
• Watch up in the air and take some pointers from the movie
• Hydrate internally and externally
• Carry some cut fruits, if you feel hungry
• Carry a neck pillow and noise cancelling over the ear headphones. Bose 700 does the job for me.