How can I improve my English?
Speaking:
Learning to speak is like learning to play the piano.
You can study music theory all day long, but if you never practise the piano, you will never become good.
You can study grammar for three hours a day, but if you never practise your speaking, you will never become a good English speaker.
Just as music students don't always practise with their music teacher, you don't always need to speak with your teacher - you can practise your speaking with your class mates.
Listening
Watch the movies/listen to songs.
Don't worry if you don't understand everything. Try to understand the meaning even though you won't understand every word.
Get Readers - these are books with cassettes/cds, so you can read and listen at the same time.
Pronunciation
Be realistic about what you can improve. If you don't live in America or the UK, you should concentrate on pronouncing letters correctly, and understanding the difference between similar sounds and words e.g. ship and sheep.
Learn what problems you have with pronunciation, and concentrate on improving them.
Writing
Know your mistakes! If you know you make mistakes with the past simple, check your writing for mistakes with the past simple when you have finished.
Redraft! When you have finished writing, check your writing, and then do it again.
Read! Learning to write without reading is like learning to speak without listening. If you don't read correct English, you won't be able to write correct English.
Don't just think about grammar. Think about meaning.
Use linking words (but, and, although...) to join your ideas together.
Use punctuation and paragraphs.
Reading
Don't translate every word. It takes too long. If you see a word enough times, you will learn it from context.
Use the Language Institute's Library.
Read graded readers.
Read slightly above your level. If you are pre-intermediate, try to read an intermediate level book. Then you will learn something new.
Do not read very long and old books. Do read things you are interested in.