I'd say the biggest advice I can give you as a long-haul guy is if you can keep some control on your (1) diet and (2) exercise on the road, you'll be way ahead.
Now, this is a more of a "do as I say and not as I do" kinda thing, because the diet control somehow seems to elude me. I don't know how it is for you guys, but we're catered with so much food that it becomes very tempting to eat out of boredom during the flight. I try to avoid that at all costs. I also try to order my meals (we can select our catering) when I'm feeling good and healthy, that way I choose salads and fish rather than Corky's BBQ and chocolate cake.
I do better with exercise. For me it's more enjoyable to go our for a run in these foreign cities if, for nothing else, the scenery is beautiful/different. I'm not a gym rat, but I'll try to get a 3-5 mile run in at least every other day on the road.
It's still a constant battle with my belt buckle, but right now we're at at impasse. Hopefully I can start gaining some ground soon.
Enjoy the world of long-haul flying, and enjoy the Triple. Once you get used to that ECL, you'll never want to use a paper checklist again.