I don't speak much Japanese, but memorized just a few very basic ones so I don't look like an asshole when I travelled to Japan.
One thing someone told me about Japanese is that there are so many ways to say the same thing depending on how formal you want to be, so I learned all the most informal ones as I figured these are the most applicable for me when travelling:
- Good morning: o-ha-YOH (emphasis on the last syllable)
- Hello: KON-ni-chi-wa (emphasis on the first syllable)
- Good evening: kon-bahn-wa (equal emphasis on all three syllables)
- Thanks: ah-ri-ga-TOH (emphasis on the last syllable. Don't roll your tongue for the "Ri" syllable)
- Where is ____ ? : _____-wa-doko-desuka?
- How much is this? : ko-reh-wa ikura desuka? (don't roll your tonge for the R syllables)
That's pretty much all I memorized. Everything else was a combination of English and body language that helped me get around (and Google Maps).