Take a real, in-person course. You can find stuff online, but the depth, order of presentation, quality of explanations, are all worse, and you get none of the

Take a real, in-person course. You can find stuff online, but the depth, order of presentation, quality of explanations, are all worse, and you get none of the structure and motivation that comes with taking real courses. That's the main reason people learn better in university (along with dedicating the time) not age.