While you likely will not know the exact questions a hiring manager plans to ask your references, you can still prepare them for the call. The first thing you should do is tell your references that they are one. While that may seem obvious, it is not always done and the last thing you want to do is have your references be blindsided by the hiring manager's call. Even if you have used certain references in the past, do not just assume they will be available or willing to serve as one again. The best approach? Ask your contacts first before giving their information to the employer.