Get to know the requirements and clear understanding of the job scope.
Dress for success you may get to work in the front as a Customer Service person / Bank teller as there are other option there.
Make sure you be there 10 minutes before your interview.
Thorough research of both the company and the position itself,learn about the work environment and transport to and from work as the work could at times involve some shifts.Have your CV and Referees well prepared and briefed and above all be honest about yourself and previous jobs/training and have questions also prepared for things that you were not able to find out about.
General Company Knowledge
STAR examples of exceptional customer service
Questions of your own will show you take initiative