A job search is basically a marketing campaign. You are the product, and the employer is the consumer - find employers who need what you love to do, your experience, and your skills.
Source: https://www.thebalance.com/job-search-tips-for-high-school-students-2060904
Job Search Tips for High School Students
Don't Be Shy. Tell everyone you know you are looking for a job.
Many jobs aren't advertised, and you may be able to get a good job lead from a friend or family member. The more people you tell, the better your chances of finding a job. Also, try stopping in at local businesses, and ask if they are hiring. Your motivation and self-assurance will impress the manager and might get you an interview.
Start Close to Home.
One good way to get experience when you are a high school student is to start by working for friends and neighbors. Babysitting, mowing lawns, landscaping, yard work, shoveling snow, and pet sitting all can be included on your resume. In addition, the people you work for will be able to give you a reference when you apply for other jobs.
Keep an Open Mind.
Don't limit yourself to certain types of jobs. This is a tough market for young job seekers, and you may not be able to find a job doing what you want to do. If you need a paycheck, keep an open mind when it comes to what you'll do to earn that paycheck.
Be Flexible.
The more flexibility you have, the more opportunities you'll be able to apply for. Plus, even if the job wasn't your first choice, it may turn out to be better than you expected.
Check the Rules.
Depending on how old you are, there are only certain jobs you can do and hours you can work.
Check the Child Labor Law (you count as a child if you're under 18 when it comes to working) regulations to see how they apply to you. The minimum age you can work at paid non-agricultural employment is 14.
Get Working Papers.
In some states, workers under eighteen may need to obtain working papers officially called Employment/Age Certificates, in order to legally be able to work. Here's more on working papers and where to get them. If your location requires them, you'll need to show them to an employer when you're hired.
Write a Resume.
A resume, even though it may not be required by employers, can help you stand out from the competition. Even though you may not have much information to include, a resume shows that you're serious about your job search. Here are tips for writing your first resume and a video on how to write a resume for teens.
Also, go to: https://edu.gcfglobal.org/en/resumewriting/
Job Search Online.
Check websites that list local job openings. You can use the job search engines like Indeed.com to search by keyword part-time and your location to find job listings in your city or town. Check your local Chamber of Commerce website (Google your city/town name and Chamber of Commerce to find it) to see if they list jobs.
Apply for Lots of Jobs.
Apply for as many jobs as possible. Keep applying, rather than waiting to hear back from one before you try for another position. Spend as much time as you can applying, and follow up by calling or emailing to check on your application.
Dress Appropriately.
When you are applying in-person for jobs and interviewing, dress appropriately. Use the "Grandma Rule" - if your grandmother would like your interview outfit, you are dressed properly.
Be Flexible.
Be as flexible as possible when it comes to your availability. The more flexible you are, the more likely you are to get a job offer. Also, know when you're available. Bring a list of the hours you can work with you when you apply in person or go an interview.
Considerer Volunteering.
Even though you won't get a paycheck, volunteering is a great way to add experience to your resume which will help you find a paid position in the future. Check with your High School Guidance office and with local non-profit organizations for volunteer opportunities.