[nehalita]

1) Food. Some flights don't offer meals and sometimes the snacks aren't enough. Bring a snack.
2) Bring something to do, the flight might provide a movie (which I would take advantage of if you can) but if it doesn't, you'll want some music to listen to or a book to read.
3) If you think you're going to want to take a nap, get one of those pillow that curves around your neck. I have trouble sleeping beause my neck hurts so I just recently got one of those pillows for my future flights.
4) Comfortable shoes. If you want to take them off, go ahead but make sure they're easy to put back on.
5) I usually layer. Sometimes the flight gets hot, sometimes it gets cold. A thin 3/4 shirt with a jean jacket is usually sufficient for me but I keep a sweater in my carry on in case.

relax. if you have a window seat you'll find it quite exciting. I've taken amazing pictures on airplanes =)