I can't sleep on planes -- at least, not in coach. So I work on my laptop throughout the flight and then, upon arrival, shut off the laptop and make the rest of the day about getting outdoor exercise and sunlight. I usually walk around all day, sightseeing, and don't stop moving till 7 p.m., when I hit the sack, taking two Tylenol PM to ensure I'll sleep through the night. When I wake up circa 7 a.m. after a long, sound sleep, I find I'm adjusted to the new time zone.
When flying across the Pacific (and at this very moment I'm en route from J.F.K. to Australia), this means many sleepless hours, of course, so I try to book flights that land at night. That way upon arrival I can go straight to my hotel and to sleep.
These strategies may not work for everyone, but they almost always work for me.