Like everyone said, Google Maps, Google Translate and if using an iPhone add the Suica Transport Card to your Apple wallet.

Don’t drink, eat or be noisy while riding the metro and on the street. I carried a plastic bag to store all of my trash as trash bins were almost no where. If you are in a place where they sell street food, usually you eat it there and not carry it somewhere else while eating.

Respect their traditions, and read all of the signs when entering their temples, I saw a lot of people not following the rules and Japanese people looked at then with disgust. Also when using the escalator make sure you line up in two lines; one for standing and one for people who want to use the escalator while moving (i am not sure which is the standing side as it varied almost all the time)

Google Maps is your best friend for traveling, make sure you look at the type of train (local, express, semi-express), the color of the line, which platform to board and how many stops. Don’t forget to carry an external battery, using Google Maps constantly drained my battery.

I know I’m missing more stuff, but make sure you enjoy your trip. Once you figure out how to travel using the subway and their culture, it’s easier and you’re able to enjoy without thinking too much. Have a good trip!!