I haven't done any long haul flying though lot's of 'long haul' overnight in another job more similar than some might think to piloting
Eat when hungry is the best one, because you can't sleep on an empty stomach, concentrate fully and just makes it uncomfortable.
Sleep when tired, or when you can. If you've been up 14hours and have an hours break, even if your not tired now, take the rest or you'll feel worse later. Though I still can't sleep during daylight very well, don't want to waste life in bed
It can be a pain though once off for a few days or even weeks, stepping into a normal living pattern again in meal times and sleeping.