Selecting and briefing referees
Before you embark on your job search, you should identify at least two referees and ask if they are prepared to act as referees for you. Your referees need to be people you have worked closely with in the last five years (at least one must have been your direct manager).
Once you get to reference stage, contact your referees and let them know who will be contacting them. It is a good idea to give them an overview of the role you are applying for so they have some time to think about your experience and can give answers that highlight your most relevant strengths.