Hi! I think that apart from how to stay hydrated the rest is very personal. The best thing you can do is to drink water/clear fluids all the way through a flight. I always have a bottle of still water on the go and take a sip whenever I can. It's become a bit of a habit, every time I go back to the galley I take a sip.
Headache-the best cure is prevention! If you are hydrated, you can snack often and you sleep properly whenever you have the chance then you will not have headaches. I very rarely suffer from headaches thankfully. There are homeopathic remedies for headaches and ailments which for me work better than allopathic medicine, but it's so personal I wouldn't feel comfortable suggesting anything to you in particular.
Good luck with this new "life"! It really isn't just a job, it's a way of living, and it's addictive!!
