Jet Lag is a buzz kill honestly especially when it comes to travelling especially for long haul flights. You can minimize the impact by using a few useful tools at hand.
1- Use the jet lag calculator, there are a lot of apps available on App Stores some basic and some quite advanced but most of them do the same thing; they tell you when to avoid light, when to add extra caffeine to stay awake. The point of this is to get your body to already prepare according to new timezone. I recently Tried the app Timeshifter but it is not cheap, there are a lot of other free apps as well, you will have to browse on app store unfortunately. There are also apps that are for Jet Lag Fix once you have got it, Jet lag Fix is an app that does just that but prescribing small exercises that help.
2- Do not eat right before and during the flight in terms of a full meal and eat when you land based on local time at the destination. For instance when you land at 11am, eat around 1pm local lunch time. This resets your body clock.
3- When you land sleep and wake up at local times. This is not easy I know but avoiding light at times suggested by Jet Lag Rooster helps and so does eating on time.
4- Stay hydrated! This is very important especially on the long haul flights.
5- Eating a protein rich meal when you land based on local time will help.
6- Some light exercise near the sleeping time will make you tired and ease getting into sleep. I usually prefer a walk around the hotel area for this.
7- If nothing else works, take some melatonin, it should help.
8 – Breathing Exercises are tremendously helpful, the simplest is inhaling and exhaling to an equal count (3 count inhale and 3 count exhale) and take it a few counts higher.