Every frequent flyer has a trick or two for every plane ride, from the simple (wearing earplugs) to the extreme (purchasing the knee defender, a contraption that restricts the seat in front of you from fully reclining). When you're on a 15-plus hour flight, precautionary measures and onboard actions can make your travels more bearable. Having profiled the world's longest flights by duration, U.S. News Travel hopes to ease your trips with 10 useful tips.What are your travel tips? Tweet your suggestions to @USNewsTravel.For many flyers, portable electronics (and the batteries that sustain them) act as lifelines. Staring into small colorful screens can calm nervous travelers and keep children occupied. But your gadgets are no good unless they can survive the flight's entire duration, which requires ample battery power. Although the top carriers provide passengers with personal entertainment systems loaded with hundreds of films, television programming, and games, this option may not satisfy everyone. If you're a tech addict, charge all of your own devices before you board.You may not be headed to the North Pole, but you should bring layers on long flights. Onboard temperatures can vary, so the ability to shed or to don clothes mid-flight is useful. Plus, you can use large sweaters and coats as blankets and pillows.Taking charge of other people's screaming and kicking children is not your job. But sometimes, polite parental assistance can do wonders. Bring a small, cheap toy along and hand it to the bored, frustrated toddler. Or promise the youngster behind you a cash reward at the end of the flight if he refrains from kicking your seat. With crying babies, you're just out of luck. But a good set of ear plugs should do the trick.You have no control over what pet dander, perfumes, or other airborne irritants your fellow passengers bring on board. If you have allergies, be prepared by either medicating before take-off or having your meds easily accessible in flight. The same goes for those with other conditions—such as migraines—which you might experience on an aircraft. Remember: There's no pharmacy on board. Also, carry any prescribed meds in their original containers in case TSA officials question you about them.Feet tend to swell at high elevations, making shoes uncomfortable. There are several ways to relieve the pressure: Wear relaxed-fit or slip-on shoes, hydrate before and during the flight, walk down the aisles, and don't cross your legs. Removing your shoes for trips to the lavatory should not be one of these tactics. This will expose your (possibly) stinky feet not only to bacteria on the floor, but also to fellow travelers.Admittedly, personal space on a plane is minimal, so do your best to hold onto as much distance as possible. Honing in on a book is the old-school way; however, using noise-canceling headphones to plug into the onboard entertainment system or your own device always does the trick.When you're on a plane for 10-plus hours and hopping time zones, you're going to fall asleep. Try scheduling six to eight hours of rest that align with your destination's nighttime. Ignore meal service, block out sounds, and turn off the entertainment system. Avoiding caffeine and other stimulants can help you catch some zzzs. Sleeping will make the flight seem shorter and help you feel more refreshed upon arrival.Ideal seat selection requires early booking and insight. The former is up to you. For the latter, we can direct you to some helpful resources. Use SeatGuru.com to pick the best available seat before you purchase your ticket. You can search by route or by airline and flight number. Additionally, you can set email alerts via ExpertFlyer.com to notify you when your requested seat type becomes available.Nothing can rile you up more than hunger. To keep you satisfied (and calm) in-flight, take precautionary steps before you board. You already know the airline's cuisine may be poor, so come prepared. Bring substantial, no-mess snacks (e.g. bagels) and a travel-size bottle of hot sauce to add flavor (or subdue it). Also, consider the menu of available pre-order meals to make sure the airline can meet your dietary restrictions and preferences.On a long flight, you can be stressed out, exhausted, and just plain out-of-it. But that's not an excuse to be rude to your flight attendants. These men and women can make or break your flying experience, and if you're stuck on a plane for the good part of a day, you want them on your side. Do your best to make nice with attendants as soon as you board the plane. Benefits can include anything from a polite answer to your questions (i.e. "How much longer?") to a complimentary beverage or a seat change.What are your travel tips? Tweet your suggestions to @USNewsTravel.