long haul eastbound go for Red eyes.
if you are in a comfortable cabin:
SLEEP and then when you arrive live the day as you if are in the correct time zone
if you are economy:
still go for the red eyes and once dinner is done have a glass of wine , recline the chair, put the ear plugs in your ear, put those acoustic earphones on your head (like the ones you get on concorde) and close your eyes until they turn the cabin lights back on. Closest thing to sleeping.
Going westbound, it really doesn't make a difference because you are simply loosing time. Have a nap on the flight and then just stick it out until as late as you can in the evening then hit the sack.
Glass of wine always does the trick for me as far as sleeping.
If you are on a short long haul like BA
which leaves New york around 11 and traveling in a premium class conduct the following steps:
1) CHeck in 2 hours early
2) Go to the lounge
3) Have dinner in the lounge, have a glass or two of wine
4) Check your email, have a shower
5) Get on board grab an extra blanket and once the faster seatbelt signs have been turned off simply recline back and go to bed...i promise you next thing you know it will be morning in London.
PARIS, FRANCE...THE BEIRUT OF EUROPE.