That's a very broad question! Do you want tricks, hints and tips on taking an international flight or tricks, hints and tips on being in a foreign country?

However, if I was to advise just two things for a first time international traveller, it would be:
i) learn a few phrases or even just words in the local language. A little can go a very long way.
ii) be prepared for and accept the fact that the rest of the world is different and some things will be different to your home country - sometimes predictably, sometimes very unexpectedly!