Whether for high school students or adults, you can monetize your expertise by teaching people with less experience or knowledge than you in that subject area. You can work with an established group like Kaplan for, say, SAT tutoring, or you could try hanging out your own shingle and making your services known either to students, parents and schools in your community. If you are targeting adults, you can create your own website or list your services with adult tutoring companies.
Walk around your neighborhood or town and I’m sure you’ll see tons of great local businesses with terrible design. However, with increasingly easy-to-use tools like Adobe Illustrator, Venngage, Stencil, and Visme, just about anyone with a creative mindset and a good amount of motivation can start making money online by being a graphic designer for local companies.