Probably already been covered ad nauseam, but I'll add my two cents:

• I always have the essentials with me. Earplugs, eye-mask, a sweater, and a neck pillow.
• I'll hit the lounge about an hour and a half before the flight and have some drinks. Some liquors/cocktails tend to put me in a more relaxed mood than others (red wine, Boulevardier, Baileys with decaf coffee tend to do the trick).
• Once on board, I'll pop a few melatonin
• I know I won't be able to fall asleep before takeoff, but I still shut my eyes and at least feign sleep. Until the pilots start to cut the engine power back and our angle of attack is less sharp, sleep isn't happening.

This strategy worked pretty well for me last week on my 4:15 redeye into MCO. Slept from maybe 40 minutes into the flight until the pilots made our pre-landing announcement.