Acceptance is one key: Our body clock was never designed for transcontinental flights at jet speed, so accept that it will need some time to adjust. Live in your own "Jet lag time zone" until you are adapted to local time.
I can do business in the US the day after I arrive from Europe, often going to bed at 7 or 8 pm local time. Getting up early (4 am), doing some work before breakfast... I accept that it will take about a week to get to a normal day-night rhythm (and avoid planning evening activities that week)
I did not find a good scheme for the flight back home (eastwards), but I found getting some sleep on the plane is beneficial; having sunny weather at home also helps to get back in sync more quickly.
N.B. It is possible to get dehydrated on long flights. Be sure to drink enough water before, during and after your flight. The symptoms of dehydration are pretty much the same as that of a hangover: having a headache and a general "bad" feeling.