Listen to radio, television and conversations in English. It is important to get used to the sound and enunciation of a language. Try to be surrounded by the English language as much as possible, even if it is only as background noise to your everyday activities.
Watch movies with subtitles in English. Although you may not understand everything people say, you can still figure out the gist of it by following the actor's actions and reactions. If you have the subtitles in your native language you will focus less on the actual spoken words in the movie. By having the subtitles in English you will get familiar with different native phrases and expressions. At the same time, you are improving your reading skills and you are also learning the correct pronunciation of those words.
Read articles and books. Reading is an important part of learning and practicing a language. Pick up texts that are neither too easy nor too difficult for your level. Try to understand the main idea and if you find certain important words that you do not know, just look them up in a dictionary. But the main thing is to find articles or books that you find interesting.
Take ESL exercises online. Several sites online teach you and help you practice grammar, vocabulary and idiomatic expressions. You can check your answers online and find out how you are doing. Begin with a lower level to make sure you know the basic rules. Once you have a good understanding of grammar concepts, slowly increase your level as you go along and see how you are constantly improving.
Talk to friends and strangers and join conversation clubs if you can. Some of the most challenging parts of any language is speaking, pronunciation and forming your own sentences. Practice speaking as much as you can. Don't be shy and don't be too worried about making mistakes. Let others feel free to correct you on grammar and pronunciation and use their constructive criticism as an opportunity to expand your knowledge of the English language.