How can I make my English perfect?

It will be hard to ever have "perfect" english. My grandfather has been practicing English for over 40 years and he still occasionally has problems with it. It depends on you, and the exposure you get to the language. If you live in an environment where you are required to speak a lot and communicate with people in English, then your fluency will improve a LOT. In general most Americans and native english speakers do not have perfect English. Just keep practicing, and when writing make sure you proofread several times.