The first thing you should do before traveling is to mentally prepare yourself for jet lag. It is important to give yourself time to adjust your biological clock before you leave, and try to sleep and eat according to the time in the country you are going to a few days before you leave.
Another important thing is to try to keep a regular schedule when you travel. It is important that you stay hydrated and eat enough while traveling, and try to sleep and maintain a regular sleep schedule. It is also important to expose yourself to natural light during the day. Natural light helps regulate the biological clock and helps combat jet lag.
Finally, it is important to avoid caffeine and alcohol while traveling. Caffeine and alcohol can disrupt sleep and make jet lag worse.