There is going to be some struggle with that much time zone change no matter what, but you can prep by staying up later, or going to sleep earlier, depending on whether it’s earlier or later at your destination. If you want to sleep on the plane, try to get less than usual sleep the night before, and then take some Zquil or Melantonin tablets once you’re in your seat. It helps to stay hydrated, so make sure to drink as much water as possible and avoid alcohol on the flight. I try to eat light the day of the flight, because a full stomach in a pressurized cabin for half a day is really unpleasant. When you’ve got a two-leg journey around the world, it’s better to wait to have a real meal at the layover city than be uncomfortably digesting 35,000 feet in the air. A protein-packed smoothie with some greens mixed in is a good idea a few hours before flying to fill up without putting your system into overdrive (bad idea: Chipotle).