Japanese people are usually very tolerant and forgiving towards foreigners who are not familiar with their myriad social customs. So you do not need to worry about making mistakes. However, there are three things in particular that are worth remembering:

Taking off your shoes

You should take your shoes off whenever you enter people’s homes, and whenever you enter some restaurants, religious buildings, clinics, hotels, laboratories, and rooms within buildings. In places where you have to take off your shoes, there is always an area at the entrance or just inside the door for this purpose. There may be slippers for you to wear (but on tatami mats not even slippers should be worn).  Many restaurants, hotels and Japanese homes will have special slippers for use in the toilet only. Be sure not to wear them back out into the main area!

Public bath etiquette

In public baths, wash yourself at one of the showers before going into the bathtub. Avoid getting your hair, soap or any foreign objects in the bath.

Eating and drinking

Some eating and drinking customs are useful to know. At most parties, people do not start eating or drinking until the toast, when someone will say Kanpai! People pour drinks for other people, not usually for themselves. It is taboo to plant chopsticks upright in a bowl or pass food from one pair of chopsticks to another, because these both mimic funeral rites. Japanese soups are normally drunk straight from the bowl with the assistance of chopsticks.

On the other hand, some things that are frowned on in other countries are acceptable in Japan. For example, it is common to make a slurping sound when eating noodles (though it is not compulsory).