just be yourself and they'll forgive you for being a foreigner.
some tips though, pretty much same as the west:
* don't jaywalk.
* do ask for a fork if your chopstick skills will force you to eat with your fingers.
* do burp as loud as possible after eating while rubbing and exposing your stomach (kidding. dont do that.)
* stay to the left side on a busy sidewalk.
* don't litter.
different from west:
* don't tip.
* don't try to hug someone unless both of you are drunk.
* don't walk on tatame with shoes on.
* don't try to navigate the subway/bus system without help....you'll end up lost.