30 useful tips for travel in Japan

Useful Japanese for Shopping
Conversation
When shopping in Japan, it might help to know a few key words and phrases In Tokyo and other large cities, you likely won't have trouble communicating your needs to shop staff using simple English, provided your needs are not overly-specific. However, some phrases and a bit of knowledge could make things go a lot more smoothly. Not to mention, it can be quite fun to have successful encounters using a foreign language while abroad!
Entering
When you enter a shop in Japan you will undoubtedly be greeted with “irasshai-mase” – which means “welcome”. This is a greeting, as well as the shop clerk letting you know that they are aware you are in the store. You are not expected to reply, although you might say “kon-nichi wa” – “hello”, just to make the shop assistant feel at ease. Do not feel obligated to engage the shop employee who greeted you, although they are always willing to help.
Asking for Help
Japan is renowned for its customer service, and if you need something, the shop staff will be happy to assist you. To signal a shop person, use "Sumimasen" (Excuse me).
You can ask if something is available: "____ ari-masu-ka?" (Do you have____?)
You can ask where something is: "___ wa doko desu-ka?" (Where is___?)
Toi-re (Toilet), Kai-kei (Register, check-out area), De-guchi (Exit), etc...
EX: Kai-kei wa doko desu-ka? (Where can I pay?)
-You can ask how much something is: "Ikura desu-ka?" (How much is this?)
At the Register
After you have selected your items for purchase, bring them to the register. In most shops, they will have some way to display the price to you after they have calculated it. This is usually done with a monitor at the register, on the register itself, or some smaller shops will show you a calculator with the price shown.
-Thank the person using "arigato" (Thank you)
-Ask for a bag: "fukuro o kuda-sai" (A bag please)
**"____ o kuda-sai" (___ please)
One thing to note is that at almost any convenience store, a bag for your items is the default. If you are only buying a drink or small item and do not need a bag, indicate this to the register person.
-"fukuro wa daijobu desu" (I don't need a bag.)
*Dai-jo-bu literally means "fine", and is a very useful phrase for indicating you are fine as you are. For example when offered something, or offered help, you can say "daijobu" to tell them “no, thank you” and that you are fine.
Other things to note
On a final note, gestures, and simple English is always a great tool in Japan. Many Japanese people love to use the word "okay", so it is sometimes easiest to communicate your needs by indicating them and using "okay?". Above all, have fun and be proactive in communicating.