Well the target you're looking to achieve is by far not easy. Yet its not impossible to do so! I think that the most important thing is practice then comes practice and practice! Speak english as much as you can. Try to get your friends to speak english whenever possible or at home with members of your family. There are many ways that you yourself can come up with. Anyway, have a look at this topic. It contains a number of
websites that you might find useful