ha, there is a point in the second response. the more you expose yourself to english, the better you will learn it. studying overseas is undoubtedly expose yourself ot english the most, which is surely the most efficient. but if you can afford to go abroad for your study, you have to come up with some other ways to study english in a Chinese context.
the "efficient ways" i can think of are watching english movies, listening to english songs, listening to VOA or BBC programs as frequently as possible, listening to some engish teaching programs(like Peter Lai's lectures, yanghua lianpian, hong'en english, American Slang and etc.), read english newspaper or magazines that interest you (like China Daily, news week, reader disgest or even 21st century and etc.), reading original english books.
a good command of english takes time. as the proverb, Rome wasn't built in a day. and ther is no shortcut in learning english. so as long as you are patient and diligent enough to do what i think is the best to improve your english, you will surely see the day when you find yourself speak fluent english.
good luck