Read a book on writing good code. There are several ones available. It's a common thing. Especially for self-taught programmers. And also if you studied... Usually once you progress to complex projects or have to collaborate in bigger teams, you have to learn this. And that's also why there is a demand (and supply) of books on the subject.

And I always recommend books. They're a way better way to learn than most of the other stuff you'll find (in my eyes). And usually written by smart people and structured the right way to teach you something fast and effective. You'll get the whole picture (something you don't get when curating your information yourself), it takes like less than half of the time of watching online tutorial videos to finish a book including the assignments. And generally: learn it in a structured way if you want to move past the basics.