In other words, don't act like you were raised in a barn! That's really what it all boils down to. Even in another culture, most people have enough sense to recognize when someone is trying to be polite. So, even if the person does make a misstep, most people understand when others are being courteous.
I'm not so sure a mandatory business etiquette class isn't a good idea for any new hires under the age of 30. I've seen many youngsters in my office who have excellent manners, but I've also seen some with manners that belong in a bar and nowhere else. Then, they look askance at people who do display good manners. It makes me wonder how they acted at home, but I have a pretty good idea.