Best way to learn English is to read, write and think in it
And speak it of course! In other words, use it!
Many years ago, when I first came to the US, I went to a small mid western town (population 15K), no Chinese (language, food, people) for almost a year. You learn English very fast that way. In fact I started dreaming in English within a week of living in America - seeing and hearing people in my dreams speaking English words that I couldn’t understand...
Of course among the couple of million Chinese Americans including immigrants many have a good command of English, so English knowledge is not a special skill for us living here, just a tool we have to have in order to survive, but some immigrants/newcomers do struggle.
If you want to learn English, you have to speak, read, write and think in English. This is probably not possible in China, but here in America, you can if you want to. Just make some non-Chinese speaking friends, stay away from Chinese media - for a while, start using English, in reading, writing and thinking, maybe even in your dreams like I did - you will learn.
By the way I think "华人" should have an "English Corner" - serious English learners should use English as much as possible...