I generally wake up early the day before. Since I'm getting in late, that usually is 6ish hours of sleep. I get up, exercise in the morning, get out and just walk around. I don't let myself go back to my room until after lunch. By about 3p, I make it dark in my room. I'll watch a few shows or a chill movie. Then it's devices down by 5p. I skip dinner and try to bring it on the flight. It's something to do for the first 30 minutes after climb out. Have a cup of coffee handy and maybe a soda but I don't do any caffeine within an hour of landing unless I'm absolutely dragging. Otherwise I get jittery.
To the person who said alcohol, I HIGHLY recommend against it. It can prevent your brain from going into REM. Better to abstain.