1. Don’t ask your host for something unless you really need it.
Japanese people in general find it very hard to decline requests; on the contrary, they feel obligated to fulfill them! If you're staying at a minshuku (a family-run Japanese-style inn) and they don’t have batteries, the inn keeper will either sacrifice the ones from her own TV remote control, or may even go down to the store herself to buy some for you, which, while admirable, probably isn’t your intention when asking. If it’s something you really need, then by all means go ahead and ask, but if you follow it up with “If you can’t do it, that’s okay,” then you probably don’t really need it anyway and you’re better off not putting your host out.
2. When you have to ask for help…
As you’re expected to not inconvenience others, only ask for the help of others when you really need it. But for the times you do need someone’s help in a big way, be sure to thank them in the Japanese fashion: with a proper gift! Before even asking for the favor you may want to buy the gift beforehand and present it to the person whose help you're seeking.
As a tourist, there are times when you’re going to need help. Maybe someone drives you to the hospital, or goes out of their way to do something. These people should be rewarded properly with a quality gift that shows you care. This is not the time to penny-pinch; give something more than that koala clip you’ve been handing out to people along the way.
3. When asking little favors…
On the other hand, when someone does a little favor for you (maybe you borrowed a converter at the minshuku to plug in your electronics), that’s when to employ those koala clips, Japanese and American flag lapel pins, Swiss chocolate bars, Dutch clogs key chains, etc. Keep in mind that you can even give food or snacks to people (which can be really fun if you can find something unique or quirky from home to carry with you, such as Swiss cow-flavored potato chips or something). In this case, it’s the gesture that counts, not how much you’ve spent.
4. Lower your voice. Yes, you!
One of the things you’ll notice when you come to Japan is that Japanese people are, generally speaking, quiet people. While they can be boisterous and loud when in groups (especially when drinking), the average person, when on his or her own, is downright demure. As a general rule, do not speak in a loud voice when having a conversation—regardless of whether the person you’re talking to is Japanese or a fellow foreigner— and don’t raise your voice when you get upset. A good rule to follow is: never talk louder than anyone else in the room, even if you’re angry. A booming voice is embarrassing to Japanese people, who generally don’t like to attract attention or have their conversations overheard by those who aren’t a part of their group, so be mindful of the other people around you. Pretend you’re in a museum if you have to.
5. Don’t dominate conversations
It’s easy to do all the talking in a conversation when Japanese people aren’t talking back the way you might expect them to. But usually your Japanese conversation partner just needs a bit more of a break in the conversation to jump in. Foreigners often mistake uncomfortable silences as an impetus to keep on talking! Resist the temptation and wait for the Japanese person to feel comfortable and start talking, or wait for a signal from the person (such as a request for more detail) before continuing. Japanese people will famously wait for you to finish your monologue before saying, “By the way…” and changing the subject, which they’ve been waiting to change for quite some time.
A good rule to follow is to insert questions into your dialogue every now and then. Questions invite the other person into the conversation and can also be used to check for comprehension to make sure the person is following your point.