For my interview, I wore a cute lace cardigan with a cami underneath, dark skinny jeans with cute little flip-flops.. didn't want to overdo it because, well.. it's a pet store. You'll probably be getting fur on you and other miscellaneous things! I didn't want to look too overdone!
Almost every interview I've had for jobs, they've asked what I can bring to their team. So think about your good qualities (punctual, organized, approachable, responsible, etc) and make sure to emphasize them! Also really try to highlight your customer service skills. Be outgoing but respectful - show them you're not afraid to be yourself and that you have the personality to reach out to people and communicate. Retail is very big on customer service, so just be yourself during the interview and try and be friendly and confident! Outgoing is a plus - it shows you're more likely to get involved and reach out to people.
They may ask you again to talk about your experience, despite it being on the application. That'll be your opportunity to go into a little more detail about any important things you may have left out on the application. Or you could always find a way to add that in.
Biggest thing is to just relax and act confident. Don't be timid or nervous, it will make you look inexperienced. You will get trained and people will always help you because they'll want their store to succeed, so you'll have nothing to worry about. :)