1. Place one of the provided pillows between your lower back and the seat. Helps ease back soreness.
2. Pack your own neck pillow, or scrunch one provided by the airline to support your neck.
3. Do periodic stretches. Place your hands on the armrests and slowly twist your torso to loosen your upper body.
4. When the seatbelt light is off, stretch your legs by walking down the aisle of the aircraft with a bit more bend in your knees.
5. Limber up swollen feet by slowly turning your feet at the ankle in circular patterns. Should help maintain good blood flow.
6. Moisturize hands and face with heavy/lasting creams or petroleum jelly. The air is very dry inflight and thin moisturizers wear or rub off.
7. Keep the air vent above you open. Dampen a facecloth, place it over your face, and aim the air vent at the cloth. Helps with dryness.
8. Bring lots of chewing gum for changes in air pressure. Ears don't always pop just during take-off and landing times, but during the flight as well. Helps with the nerves as well!
9. Wear loose fitting, slip on shoes. Feet swell, and if you take shoes off at any point in a flight, a shoe that just fits can be painful to put back on.
10. Wear loose fitting clothes. Inflight dining and drinking may leave you feeling bloated.
11. If you are wearing pantyhose or tights make sure that you moisturize your legs well. The dryness inflight can make legs feel very itchy in tights or pantyhose if you don't.
12. Try and drink as many non alcoholic beverages as possible. Perhaps bring an extra bottle of water with you.
13. When traveling with a broken arm, or toe, etc., make sure that your doctor has provided you with adequate pain medication. The compression inflight can make a broken bone feel excruciatingly painful.
14. Try not to keep your hair in a ponytail, or use hair clips in the back of your head. These will dig into your head after a few hours of the rigid seat backs.
    

More How To's from your Guide to Air Travel