Here's my three tips for sleeping on a plane.
1. Seems self-explanatory but staying up late and getting up early the night before do wonders. You can't sleep if you're not tired.
2. Don't drink booze or lots of water, for aforementioned piss reasons.
3. Invest in Bose noise canceling headphones. They are expensive but they work like motherfuckers. Can't hear anything. My pops got them for me for Christmas last year and they're one of the best gifts I've ever gotten. Thanks Dad.