I am blessed as some of my 37 year old Friends get bad Jet Lag when they travel. I am very fortunate that I can operate on 4 hours of sleep if need be but I generally get 6-9 hours of good sleep . This is what i do to prevent Jet Lag
I take a flight leaving SFO at 6 PM and connect via Istanbul arriving Tel Aviv at midnight. On the first flight I try to get 8-10 hours of sleep, Then I stay up until 1-2 AM TLV Time. Before my flights I take Melatonin starting 5 days before and on the plane 30 minutes before I want to sleep. I really don't do the go to bed an hour earlier as I just listen to my body.
On the day of travel I do light stretching and take a walk. I always like getting to the airport early to avoid any stresses and go to the lounge before the flight . I will adopt a High Carb dinner the night before to help with sleep. In the lounge I'll have a cocktail or Whiskey. On the flight I'll drink some Wine too with water as well. Every body is different.
I bring along an airline amenity kit just in case one is not provided with a good eyeshade, socks , toothbrush and toothpaste. Generally for the first part of the flight I stay awake and enjoy a movie. When I go to sleep I put on my noise cancelling headphones and good music! I'll then get up and walk around the cabi to get a snack and something to drink.
After this I'll have the Breakfast and then stay up until 1-2 AM local time in Tel Aviv. I enjoy a nice shower at the Istanbul Lounge. Turkish Air offered blocking the middle seat on all flights for $544 so I will lift up the leg rest and use the middle seat's space to help me sleep. I also love having the map on on one TV and a movie on my own TV. Its totally worth it to purchase an Extra Seat. United charges a lot for Premium Economy and I like to be towards the front of the plane.
I also like bringing my own movie snacks like Milk Duds, Popcorn that I buy from the Farmers Market and make my own Snack Mix and trail mix. I will have this stash in case of an emergency too.
Anything to make the flight easier is fine by me! Hope these tips help.