Moved to part-time and temporary employment.
You should dress smartly - suit, smart dress, smart skirt. Clean and ironed, not creased. Hair should be appropriately styled - tidy, clean. Any makeup should be subtle. Same with jewellery and any scents you want to wear.
They'll probably ask general interview questions - strengths, weaknesses, previous experience, skills, what you can bring to the job, any ideas you have. They can also ask you about scenarios about how to sell, what to do with a difficult customer. They might also ask you to prove your skills by you telling them when you've demonstrated a skill.