Immerse yourself in English. If you can, travel to an English-speaking country and simply surround yourself with the language. If you can't travel, enroll in a language immersion program, a class in which English instruction is given in English; no other language is spoken or written in the class. According to Ken Stewart, the 2006 American Council on the Teaching of Foreign Languages National Language Teacher of the Year, an immersion program is the "next best thing" to learning English in an English-speaking country.
Surround yourself with English at home. Buy movies, CDs, and books in English, and listen to or read them on a daily basis. Listen to English radio stations and television programming in English. Surrounding yourself with English outside of the classroom helps you learn the language faster and with greater accuracy.
Read good English grammar books. You can't learn English by memorizing English grammar books, but you will need them as reference materials. Use the grammar books to help you memorize grammar rules that you have trouble understanding. Try to find a book with lots of exercises that you can do to review on your own time.
Work with others. Find a teacher, tutor or native English speaker to work with you in order to point out what areas that you need to study more. Take time to speak with this person often and ask this person questions that confuse you. Also, ask your tutor to review your English writing.