Many thanks to @quite-unlike-tea and @HerrDouglas who have given me lots of advice on last post.
I am 27 years old now. I had my first English course around at the age of 10. At that time English was not a course being taught at elementary school, and it usually was taught starting in middle school. But my mother found a teacher to teach me simple English words on Saturdays. I mainly learned basic vocabulary, such as numbers, months and letters.
From grade 7, school began to give English classes to students. English is an important course because it takes up 120 scores of the 750 sum scores. And this score will decide which high school you can go to. The higher your score, the better the school, and the greater opportunity for you to be admitted to a top university.
The first big change happened in grade 8. Our English teacher spent several weeks teaching us the English phonetics systematically. I learned well about the phonetics, and as a result I could pronounce an English word by reading the phonetic marks, while most Chinese students were using Chinese pinyin to help them understand the pronunciation of English.
Gradually, I found I had an interest in reading English short stories in textbooks or test papers. They provide funny stories and sometimes some good tips about life, which was different from the serious articles in my Chinese textbooks. The English examination was easy for me, and I even enjoyed reading the articles included on the test. I also worked hard to memorize lots of vocabulary, and that helped my reading a lot.
The second big change happened at my university. I decided to improve my pronunciation at that time. I found some good tutorials on the internet and bought a textbook teaching American English pronunciation. The writer of the book is Taiwanese and he sounds like an American native. I spent one month following the audio and repeating his pronunciation to correct my accent. After repeatedly practicing, my tongue got used to some difficult pronunciations and I felt my accent improved a lot.
At the same time, I use some ESL (English as a Second Language) audio material to do shadowing practice. Three months passed, and I learned a lot.
Having a lot of spare time at university, I also tried to read English novels. I finished the first 4 books of Harry Potter. I was confident in my level of English, but I didn't have an opportunity to talk with native English speakers. There were no foreigners at my university, and my English teacher was also Chinese.