They ask a lot of questions, so remember a lot of relevant work experience from before. Dress trendy, employees are the faces of a company and they're all about trends.
Availability is key. The more hours you can work, the more likely they are to hire you.
Make sure they know that your available whenever they may need you. that you will take all the hours they can give you.
Go through typical scenarios that would happen in a retail workplace, they ask a lot of "what would you do if..." questions.
Be yourself and dont be scare, they hire a lot of people.
Dress business casual
Be upbeat and prepared to answer questions related to what is on your resume as well as any other skills related to why they should hire you
Knowing the business
By preparing you should make sure you're dressed professionally due to their strict dress policy, make sure you have a notepad and pen to write notes and of course your resumes and/or cover letter.
If you have experince in retail you will be fine