No need to prepare. It's like interviewing for McDonalds or Burger King. They'll hire anyone. Once you pass the drug screen you will not be drug tested again (no random testing). Be prepared to be lied to about promotions, pay raises, and incentives for working there. The GM will not be at your interview but will make his presence known and try to look important. This is just psychology to try and get you to respond to orders. Don't be intimidated.