I think it would be good that you mention that your are detailed oriented, organized, work well under pressure, are capable of multitasking, or understand the importance of confidentiality of information - whatever fits you. These are things that all tellers, and anyone working in the banking industry should possess. It's important that you understand the fragility of the information that you will be handling. Also, that you understand that due to what the job entitles (that is handling people's money - sometimes large sums), it is very important that you work well under pressure and that you pay close attention to details.
Wear the most business formal clothes you can find. Seriously, clothing is extremely important, ties or scarves depending on who you are. Be confident in your own abilities and don't stumble. When I applied to chase I had no banking experience, just normal pet store and clothing store retail, but the way you present yourself matters. Highlight how you have constantly dealt with cash or highlight any moments you feel that you have shined brightest as an employee. You should be prepared for a 3-step interview process as well: a phone interview, an online impersonal video-recorded interview, and an in-person branch interview. If you are bilingual, make sure you point that out as soon as you are able to, because in banking retail, the more languages you know, the better.