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I know there are centres that teach Portuguese - just don't know where. That should be the easiest way. If you want to learn it by yourself, then I guess it's the usual: besides having to learn grammar, look up vocabulary, and manage the pronounciation, it's always good to practice your hearing by watching films or listening to songs (in the beginning, preferably with subtitles in Portuguese). Cartoons from your childhood are always good because you can easily keep up with the story and shouldn't contain too much slang... Don't know if that's of any help really.