If you want to get a basic understanding of the language to go around there instead of spamming preset phrases, I can recommend checking out this page and learning everything up until basic grammar (basic grammar included). While not required, learning Katakana might help you with identifying some words that come from English.
From then on, for vocabulary, just write down a list of words that you may need. For instance, if you’re going to a restaurant, you might want to write chopsticks, fork, knife, meat, fish, vegetables and so on. Then, look for the translation and memorize those. That way, you won’t be forced to saying specific phrases that you may forget when you most need them.
Anyway, that’s my advise. Going everywhere with a smartphone and google-translating everything is another option, and I’m sure there’ll be some others. Just pick the one you think will benefit you the most.