Your best option is to build a blog and learn by doing. You’ll actively learn how to choose keywords, apply them to a blog post, and also you’ll have something to show on a resume when you want to freelance. “I read about it a lot” isn’t useful to anyone who wants to offer money for services. They want experience, and this will give you some.
I’m sure you’ll be fully aware having read up on it before, but SEO takes 6-12 months to work on new blogs, so you’re unlikely to be in well-paid SEO employment by the end of 2020 unless you go for a tiny-wage internship.