Most tarot readers run their own small business. Depending on your local laws, you may or may not need a business license to start out, if you are making less than a certain threshold.
But considering your current age, it may require additional research for some aspects of legality.
But moving on: most tarot readers I have met either do it as a side job, or finding work becomes a full-time occupation in itself. I'm really not exaggerating. I have known people who spend more time visiting local businesses asking permission to set up a table than they do with actual readings.
Doing something creative in nature is a lot more about business savvy and not nearly as much about actually doing the creative aspect. The same goes for tarot reading, palmistry, photography, music, and more. It boils down to marketing and work selling the concept of what services you offer.
@prsona: Thank you, and I understand about the small business and the difficulty of finding work aspect of it. I will definitely do some more reading on starting a business at my age. I want to earn some money to save, and it's not my dream job. Do you think having a blog would help though?
Actually, yes. Social media is the way to promote business these days. Really: There are people who do more social media than actual work, and are successful because of it. There are some excellent guides online.
Having a blog is great, but also a Facebook, perhaps Instagram, Tumblr, or even a YouTube channel, and more, will all be helpful.
There are a few tarot readers on YouTube who do some broad periodic readings, and use it to promote their services; one person in particular I have watched will do reading videos for a person -- and he uses a nick name they both agree upon to help preserve privacy -- as well as reviews of different decks, and lessons on divination using tarot.
Another I know of will make a post on Reddit with her weekly readings, though I'm not so sure how well that's received.