Many of us tend to dump our carry-on luggage into the overhead bins. Even though you might have a huge list of items to carry-on, try to keep the weight of your carry-on as light as possible.
Many a times, I've seen passengers removing their seatbelts after take-off. It's always a good idea when in your seat to stay buckled up. If the plane hits unexpected turbulence, the seat belt keeps us safely in our seats.
For those of us who love a good cocktail should consider not overdoing it. The high altitude and cabin pressure makes the alcohol affect us more strongly. Moderation is always good, no? Water and fruit juice are always ideal in-flight beverages, especially if you're taking a flight to a destination where you'll have to deal with jet lag. If you haven't brought your Ipod or magazines, take out the in-flight magazines offered on the airline you're flying and watch a little TV, listen to some music or the movie.
In the end, safety first, of course, but, if you are a nervous flyer, remind yourself that you're bigger than your fears and wherever you're jet setting to, it will be well worth the adventure.