Drink lots of water, avoid over-eating and do not drink too much alcohol and caffeine.
Wear comfortable, loose-fitting clothes for the flight. Pack a light sweater and a pair of cozy socks for warmth.
Ensure that your one-piece cabin bag is small enough to fit in the stowage bin for more legroom and less clutter in your seat area.
Bring a moisturizer, lip balm and eye drops with you during the flight.
Pack some light snacks, candy and bottled water in your cabin bag.