I worked in Chile, Argentina, Ecuador and Mexico almost 50 years ago. Watching TV, listening to radio, and going to movies (with English subtitles) really helped me a lot. Unfortunately, I just learned a few hundred nouns, a handful of verbs, and almost no grammar, so I sounded like a complete idiot. But, that rudimentary learning plus a lot of hand gestures got me by. Some friends in Chile were very complimentary on my pronunciation and urged me to go farther.
The most amazing thing was a guy I met in Chile who spoke absolutely PERFECT American midwest English. I asked him where he had studied in the States and it turned out he had never been to the USA. He taught himself pronunciation by watching American movies! But he also had excellent grammar as well.