Get a white-noise generator. I use https://f-droid.org/repository/browse/?fdfilter=noise&fdid=n... on Android. I find it more effective than earplugs for drowning out engine noise and crying children.

Don't drink alcohol if you want to be productive - although if you're just going to be watching in-flight movies, knock back as much as you can ;-)

If it is not too late, request a special meal. I usually choose vegetarian (because I am), but you can go for Kosher, Halal, Vegan, etc. You usually get served first and the meals are generally of higher quality.