I'm worrying about my interview tomorrow,can anyone help?PLEASE!?

I am a student and a new canadian as well.English is my second language,I have got an failure experience at starbucks yesterday just because I haven't catch on one of their questions.So they thougut my English is not good enough.But I think I can communicate with others, just a little slow.What can i do for the interview in tomorrow afternoon? How should i perpare for that ? I really want to do sth before I enter the university ,I need that job ,could anyone help?