You will compete with many other job seekers (actually more than fifteen in average) for the job. And since the experience or education do not really matter for the interviewers, your answers to their questions, and your ability to demonstrate the value you can bring to their bank, will decide whether they hire you, or someone else.
The right personality for the job
Try to show them that you know what it takes to be a great teller. Demonstrate your listening skills, ask relevant questions, show enthusiasm for the job, and understanding for the rules they have in the bank.
If you can, learn something about their product portfolio, their values and goals, and show them that you want to work for them, and not just for any other banking institution.
Some of the common questions
Why do you think you are the right person for this job?
Interviewers try to find out if you understand the role of a teller, if you know what would be expected from you. You should focus on customer service and sales, good level of customer satisfaction and your skills and abilities that will help you to achieve the great level of customer satisfaction.
Why did you choose our bank?
Say that you like the working environment, and the way the tellers approach the clients of the bank. If you are a client, do not forget to mention it, stressing your satisfaction with the work of the tellers in the bank. You can also say some good things about their product portfolio.
It can be either a question, or (and more commonly) a role play. You will play the teller and the interviewer will play the client. Try to uncover the needs of the client with targeted questions, and show them how the product you offer will satisfy their needs. It is not an easy exercise, but once you see some good role play examples, and practice your talk with a friend, you should be able to deal with that to a great satisfaction of the interviewers.
What are your salary expectations?
Try to emphasize that the job itself, and not the salary motivates you. To say that you would accept their offer is probably the best option, since banks offer the same salary to every new teller, and they will not negotiate with you anyway.
More questions, role play examples
Jacob Gates, a reputable career coach from Cambridge, runs a website that specializes only in bank teller interviews. The website offers sample answers to ten most common questions for tellers, and many other useful resources. You can find it here: BasnkTellerInterviewQuestions.com