I travel long haul a lot, and I try and work out when I need to sleep during the journey. When I arrive I try to get sleep patterns right quickly, but not at all costs. Try to get through a whole day is miserable. I would tend to drop my bags, go for a walk, have lunch and then a couple (no more) hours kip and go out again after a shower. I would then try and stay up until about 11 and if I got six hours sleep I would be pleased.
Jetlag gets people in different ways, and on a flight round the world it is very difficult to avoid totally. The usual boring tips apply, lots of water, no alcohol go out in daylight. I'm never very good at avoiding alcohol on flights though, particularly Qantas as it is usually ok wine