I found a vary of jobs that I think are very good for teens. Such as babysitting and working at an animal shelter. I think these are good jobs to have as teens because it instills responsibility and character. Also it is very flexible which is very good for teens considering we have very busy schedules.
Teens have so many extracurricular activities that can take up time after school. These jobs allows you time to do those things and your homework. To get ready for an interview you might want to look not so much professional but maybe presentable. So don't show up in shorts and a tank top. As for the difficulty, it was fairly simple to find a job online. There are so many choices the only hard part I think is finding the right one and which ones apply to your schedule.