Travel writer Ramsey Qubein (aka @DailyTravelTips on Twitter) flies over 400,000 miles annually as a contributor to a number of major news and travel publications. He recommends always staying hydrated while flying. “Drink lots of water and avoid caffeine and alcohol. Of course, this is not always easy for passengers in middle seats (getting up to the bathroom can be annoying) or those enjoying premium cabin amenities.” When you land, drink as much water as possible. “Cold water is even more refreshing,” he says. Drinking water is encouraged on board, but make sure you never do these 18 things on an airplane.