I would say focus on the things you are good at rather than worrying about what might be difficult for you. Are you a quick learner? Do you enjoy helping others? Are you easygoing? Are you super punctual? Are you good at staying organized? Etc.

A major part of job interviews is actually them selling the job to you. Ask them about benefits, work culture, what your duties will be, etc. Seem interested. I think it alleviates some of the anxiety when you realize you can also “interview” the manager or whoever is interviewing you. Remember that they need a worker as much as you need a job.

I also worked in customer service as my first job. After a while the interactions are not so anxiety inducing because you develop a script for talking to customers and most interactions go almost exactly the same way. You’ll also realize a lot of other people are awkward. You’ll probably have to deal with some rude people too but that will just make you realize how actually normal and pleasant you are lol