These rules might fit under the rubric of a traveller's ethic, a set of precepts that allows for greater enjoyment and less hassle while travelling, while at the same time protecting the environment and culture of the place visited. These rules can be considered analogous to camping rules like "take nothing but pictures; leave nothing but footprints."
1. Never live more than twenty minutes away from an international airport. Allows for quick escapes.
2. Go native. If a Parisian or a Madrileno comes up to you on the street and asks for directions, you'll know you've arrived.
3. Be spontaneous. Plans will change without your will or knowledge: Planes will be delayed, buses will be missed, one of you will get tired or sick. Holding to a plan will just make things worse. Do not hesitate to completely abort a trip, either, should worst come to worst.
4. Never check bags. Nothing ruins a trip faster than losing your luggage, though I will credit the airlines with being more careful these days with matching bags to passengers. Not checking bags has the side-effect of forcing the traveller to bring only what is essential, because it all has to fit in the one carry-on bag.
5. Country-bagging is not true travelling. Country-baggers are people who try to get to seventeen countries in sixteen days and end up getting no real feel for a place. The number of countries one has seen is no basis for experience.
Still, if counting must be done, two further rules:
Only international travel counts. Seen one US berg, pretty much seen them all.
Only going beyond the transit point counts. That means out of the airport, train station, bus station, wherever. You've never been someplace if you see the inside of its airport. This is the only reason I can't count Japan.
6. Use the language. Americans are known far and wide for being callous outsiders; the principal reason being that they refuse to use any language but their own. Language is a source of cultural pride. Using the native language, no matter how poorly, gratifies the ego of the person you're speaking to, and they will give you a wide latitude. This is why I have never had difficulty with the French: I speak French to them, not automatically, and callously, assuming they all speak English.