You dont need a tie for a staples interview.
Dress shirt, (I recommend a color other than white. White dress shirts without a tie look like youre using your one 'church' or 'good' shirt. And I wouldnt wear a tie to a staples interview.) slacks, nice shoes. Take out earrings, etc.
Common sense shit.
Speak as proper as possible, but dont overdo it or be a phony.
Don't be like "Well yes absolutely sir gee golly". Interviewers are people just like you. The main thing they wanna see is that youre not gonna fuck around and you're not hella lazy or dumb. Be professional, but its ok to be a little conversational, especially when they make a comment first.
Just act like youre professional, about your buisness, and not gonna fuck around.
Think up something beforehand to say when they ask you why they should hire you.
Be like "Im professional, responsible, reliable, I am good with people" etc.
You may not have any work experience, so make up some bs like "I used to help my aunt at a hotel checking people in" or "I used to work at the restaurant of a family friend" etc.
If they ask why you didnt list it, just say "because it wasnt an official job and I just helped out every now and then"
If you DO have work experience, make your last job sound like more than it was, or beef up what youre gonna say about it. Always say 'you learned customer service' at an old job or if you have no job experience just say 'I'm professional and good at dealing with people'.
Dont be hella nervous. It really aint shit. You just gotta go in there and show that you aint gon fuck off all day and that youre about your biz.