Dress Nicely even if the job is casual! I remember a funny anecdote by a Youtuber who said when he was 17 he got a job at mcdonalds very quickly because he showed up to the inverview in a suit and tie.
Make sure to smile and be relaxed. Laugh at any jokes that may be made and partake in conversation. Make sure you are clean as well. Fix your hair, brush your teeth, etc
Eat a good breakfast and get enough sleep. Doesnt have to be hard: Just 8 hours should be enough, eat and drink coffee and you should be ready. I recomend streatching via yoga to get yourself ready for the day, not just for interviews, but in general
Do your research! be knowlageable about the company and the description and desired points of your job
Make sure you have prepared a resume or any documentation that proves you are exempliary. Also bring a notebook so you can write down any important information you are given
Think of reasonable and intellegent questions about the job to ask. You get to talk too!
Show up early! You want to show up early for an interview to show dedication to the job. You can use extra time to look around the place and see how things work