Drink water, not alcohol. Eat the first meal, take some melatonin and a couple of swigs of Benadryl, and you should sleep fine. If you don’t drop off straight away, ear plugs and some reading should do the trick.
As always, try to live your day before a long flight on (at least) half the time difference between here and there. (e.g. 6 hrs between Manc & Chicago, so I...in Chicago...get up about 3 hrs earlier than normal, get some exercise & fresh air, eat on a Manc timeline, eat the offering on the flight and bed down for the night ASAP after the meal, which is when they usually dim the lights.)
On a WESTBOUND flight, do it the other way, if you can...get up about 3 hrs later, so you don’t experience a 30 hr day! Jet lag only an issue EASTBOUND!!