[Tsuwabuki]

You will probably be offered a lot of help, and much will NOT be helpful.

If I get the feeling someone is going to attempt English in a painful or useless way, I simply jump in and say "ii yo, nihongo wa daijoubu, douzo" or "It's cool, Japanese is fine, please continue." If I can speak Japanese better than you can speak English, let's just go with Japanese, okay? For someone unfamiliar with Japanese grammar and construction, Engrish can be completely unrecognizable and therefore completely useless. At least getting to learn the basic sentence structure of Japanese will help when you have to decode English words crammed into Japanese grammar.

I would suggest you get a copy of Pimsleur's short course. I crammed before coming to Japan and it really covered the important things, and how the answers would be given. I understand grammar quite well, and the last nine months have been a lot of vocab work. Where, what, how much, numbers, etc should be learned quite easily even if you're only repeating without a great deal of understanding the underlying structure.