Australian, so in feel you. In reverse order of importance: 
3. I tend to have to hit the ground running, so I unlimit my caffeine and sugar intake when overseas.
2. Fly business overnight: being able to rest, even if not sleep properly, really makes a difference. 
1. Half the stress is anticipation: I try to travel very Zen. Once I'm at the first airport, I chill. Don't have any explicit goals for working on the flight, don't stress security, delays, etc. Calm and stillness.

Also when I travel for pleasure with the family, I have an ugly Hawaiian shirt I wear to emphasize to myself that this is *not* a business trip! Sets the holiday mood early...