As a student I would tell you that you need to pratice, if you have the chance to visit an english speaking country it's great. But if you don't have this opportunity the more effective exercise, which at least seems to work for me, is reading out loud. As far as I know it helps the muscles of your mouth to get used to the sounds of the new language. I don't know if it's really true or pure rubbish. I would like to have a teacher input about my comment.
Student or Learner