The best method is not to look for a method and not bother yourself with it, but simply to teach.
Learn, practice and immerse yourself in the language as much as possible and devote as much time as possible to it.
In short, observe persistence.
Why reinvent the wheel if English is taught in schools. There you can learn the language well, and then there are many ways to improve your skills. Television, films, video / audio lessons, and so on.