When flying eastwards, I prefer to prepare for the change of body clock upfront towards the early hours, by simply getting up in the 4-5 days before the flight, 1 hour earlier, each day. So, with a 5-6 hours time difference, I already do have 80% of the time change upfront and the arrival comfort at the destination is pretty well undisturbed.

When flying westwards on a night flight, I tend to do the opposite, though with less hours (only 2 or 3) and usually not the departure day, since this tends to be early due to a SH flight before the LH. Transition to the arrival time zone, makes me wake up very early in the morning and that gradually shifts into a normal time pattern, within some 3-4 days.

When flying westwards on a day flight, I tend to just stay awake (with maybe a 1-2 hours nap, around midday/early-afternoon, departure time-zone). That's an exhausting day, though with one night, roughly back on the arrival time zone.

No alcohol, a lot of water, limited food. Better a little hungry, then stuffed, so to say. Snacks are easy to get.