Flying is an ordeal, involving dangerously low oxygen levels, cramped seating, cranky passengers, and less air humidity than the Sahara.

Given that, here is a comprehensive list of steps for a more bearable flight.

BEFORE YOU GO

• Many airlines allow you to book specific seats while purchasing tickets online.  Take advantage of this by visiting SeatGuru, which offers interactive seat layouts for all airplane models.  The color-coded layouts detail the seats with hidden pluses or problems.
• Fly First Class if you can (I know, me neither).  Still, the perks go beyond free champagne: First Class passengers have more leg room and up to three times the amount of oxygen as passengers in Coach.
• While eating airplane food is a general no-no (see below), and more and more airlines have done away with free domestic meals, special ordering meals for international flights makes sense.  Ordering a vegetarian/hindu, kosher, muslim, or diabetic meal means you’ll get served first & your food will be healthier and fresher.  Call your airline at least 24 hours in advance to place an order.
• That said, try to bring your own food.  Special meal or no, airplane food has preservatives, salt, and may have been dropped on the floor before serving.  Bring your own high-carb, low-fat, low-sodium snacks (i.e. vegetables, fruit, or food made with whole grains).  Pack them in something like this attractive lunch bag from Magellan’s, which separately stores drinks and food, rolls up easily, and will be useful long after your trip.
• Prepare for the flight by creating a toiletries comfort kit.  Flight001 has pretty and convenient jet comfort kits; you could probably do just as well assembling your own kit from the drugstore.  See below for a suggested pack list (Flight001 also offers a tempting Mile High Kit, although I wouldn’t use it on the airplane).
• Another kit worth buying/assembling is an eyeshade, blanket, and pillow kit (a neck rest, socks, and soft earplugs are also helpful).  More and more airlines charge for blankets and pillows, neither of which are washed between flights (ewww).  Magellan’s also offers the Seat Wrap for $6.95/$9.95 (full).
• Start resetting your internal clock several days before the trip.  Try to sleep, eat, and wake up at the correct times for your destination.
• Pack light.  This will save you time at check-in and keep you from racking up exorbitant surplus baggage fees.  Check with your airline, but the normal carry-on allowance is one carry-on piece and one personal item (a purse, a laptop, etc.).
• Dress in loose layers.  Loose, because you will bloat.  Layers, because cabin temperature varies widely.  Your feet will swell the most, so be sure to wear comfortable shoes. Many experienced travelers also carry travel slippers or socks.
• Arrive at the airport early.

IN-FLIGHT

Former flight attendant Diana Fairechild is a leading champion of airplane passenger health.  Many of the following suggestions are paraphrased from her highly recommended articles Fast Facts By Diana Fairechild & Airline Meals.  I’ve also corroborated her information with other sources, including this Dealing With Jet Lag article.

• Don’t eat airplane food.  In fact, the best thing to do is to liquid fast while on board.
• If you must eat, eat only low-fat, low-sodium carbohydrates. Small amounts of protein and fat are OK, but both fat and protein
  require more oxygen to digest, and will increase bloat and other jet-lag symptoms.
• Drink water every hour (BYOB).  Platypus Water Bottles are refillable, collapsible, and come in three sizes (you can also buy
  2 1-liter bottles for $12.85 at Magellan’s).
• Avoid dehydrating foods and drinks (sodas, alcohol, sodium-heavy food, coffee, and tea).
• Humidity in the cabin ranges from 1 to 10 percent–less than the Sahara.  So moisturize like crazy.  Use eye drops, spray your face with water, rub unscented lotion everywhere, use lip balm, chew gum (stimulates saliva), and spray hair with a light leave-in conditioner.
• This is weird, but Fairechild recommends you coat your nostrils with oil (that’s inside the nostrils).  Don’t use petroleum jelly, but a vegetable or nut oil will work.  Fairechild argues that oiling up prevents the delicate nose membranes from cracking in the dry air (germs in the air enter via the cracks).  I couldn’t find scientific evidence supporting that, but the practice appears similar to ayurvedic nasya.  Hey, Deepak Chopra recommends it (and he’d never try to sell you anything you didn’t need).
• Michelle F. highly recommends saline nasal spray instead of the oil. “Ocean is the brand name but every drugstore carries their own brand as well.”
• Exercise every hour for several minutes.  Get up, walk around, do lunges.  Here’s an eHow on Airplane Exercise, and a pretty “Flying Pilates” PDF from JetBlue.  The really gung-ho can buy an airplane exercise book
• Melatonin and the Argonne Anti-Jet-Lag Diet have their fans, but are unnecessarily complicated, and will probably only give you a headache.
• Magellan’s has a product called No Jet-Lag (buy it here).  Some people swear by it, while others think it’s an useless placebo.  Has anyone used this, and if so, did it work for you?
• Another favorite medication is Dramamine (drugstores) event of an emergency, however, sleeping pills hinder your ability to respond effectively.  In addition, the near-comatose state induced by sleeping pills, combined with their dehydrating effect, increases the risk of deep vein thrombosis** complications.
• If you haven’t already, set your watch to your destination’s time.
• If you will arrive in the morning, try to sleep on the plane.  If you arrive in the evening, sleep once you get to your destination.

** Complications related to DVT are well-known travel risks, discussed here, here, and here.  Because we love controversy, however, here’s a Seattle Times article which effectively argues that the popular fear of DVT was manufactured by drug companies seeking to promote blood-clot drugs. Of course, frequent exercise and water intake are probably a good idea anyway.

AFTER

Once on the ground, break your fast with a good meal, and then sleep that evening (here’s where sleeping pills might be a good idea). Fairechild also recommends that you bathe ASAP.

For the next few days, make sure to eat nutritiously, take vitamins, and get sufficient sleep, to combat any bugs you may have picked up on
the plane.

A favorite of business travelers outside the U.S. is Berocca, a fizzing tablet with obscene amounts of vitamins. It’s well known to prevent hangovers, but also helps ward off sick spells.

PACK LIST

• Water Bottle(s)
• Moisturizer
• Lip Balm
• Hand Sanitizer
• Water-Filled Spritzer (cheapo version of this)
• Eye Drops (particularly if you wear contacts)
• Mint Gum (mint settles the stomach, gum pops your ears, both freshen your breath)
• Pillow or Pillow Case
• Blanket
• Eyeshade
• Neck Rest
• Earplugs (soft ones)
• Headphones (check your airline’s policy–some still provide headphones free)
• Socks or Slippers
• No Jet-Lag/Dramamine
• Dental Kit (toothbrush, toothpaste, floss, mouthwash)
• Low-Fat, Low-Sodium, High-Carb Diet (cereal, vegetables, fruit, pasta, some candy (OK, that might be cheating))
• Entertainment: magazines, Sudoku/Crossword books, a deck of cards, travel board games, paperbacks (Paradies Shops allow travelers to buy, read and return books to any Paradies stores for a 50% refund).

Tips we missed?  Leave us a comment.

UPDATE: Lifehacker pointed me to the following links:

1) The Independent Traveler tells you how to sleep on planes (favorite tip: turn your neckrest around so it catches your chin).

2) British Airways offers a personalized jet lag advisor, as well as supplementary information on your body clock.