First of all I just would like to commend you for wanting to work as a high school student. I work with High schoolers outside of my job, and only a couple are interested in working. What are you passionate about? Do you love technology, animals, people, video games, etc? When you try and get a first job, try to keep these in mind. It's always great to go home happy at the end of the day, but if you are going to be helping other people throughout the day, then you also want them to go home happy as well. I started off working at a mall just applying to different places and got a job at a clothing store. I liked the job a lot, the pay was not good, but I really enjoyed working there, once I began to drive and become more independent, I knew I needed a better paying job. So I used the experience as a stepping stone to get to something I was passionate about, technology. I worked at Best Buy after the mall job, and eventually found my way to Apple!
So no matter what job you decide to get, I would say keep your future in mind. I was always looking at the short term, and I probably would've gotten to where I wanted to be faster if I had looked into the long term. A company called MOSAIC is a company that hires people for multiple brands to be a brand ambassador, so you might want to look into that. Good luck with your future career!