What are some of the best means to improve one's English?
There's no single answer to this. Different people learn in different ways at different speeds. It also takes a long time to learn a language- there are no quick or easy answers. A language embodies the culture of entire people, so acquiring any language takes a long time. Basically, I think that a lot of practice, determination and the ability to accept that whatever patterns you learn, there will always be other patterns that may conflict or substitute help, and acquiring a sense for the music and rhythms helps too.