well breathing to reduce your anxiety is always good.

interviewers typically want to know about you and what you have to offer the company so it is good to have a bit to say about yourself prepared. like youre a hard worker, detail oriented, motivated, self starter, offer good customer service, good communicator.....stuff like that

they are going to want to know that you will work well with consumers if you are going into retail.

just repeat what you want to say over and over to yourself so you don't forget it when you get in to the interview. most importantly, relax when you talk to them. good luck