First, practice pronunciation and intonation through reading comprehension. This should be the most conceivable method, so you must choose a movie with moderate speech speed to imitate it. And don't think about watching the lines of the whole movie, it's impossible and very inefficient. You can choose a place you are interested in, about three or five minutes, then listen repeatedly, listen and read, and finally start and end at the same time as the lines.
Second, learn authentic expression through lines. This method requires us to take out our lines and analyze them after watching the movie. If you find very authentic words and sentence patterns, accumulate them and use them in everyday spoken English.
Third, learn British and American culture through movie plots. Many historical films and documentaries have rich cultural backgrounds. If we find a prototype of a historical event or a metaphor of a political event in the process of watching a movie, we can search for information through the internet after watching the movie and find out the ins and outs of this historical fact. We can also learn about a character's life through movies and deepen our understanding of British and American culture.
From Xia Zi, a down-to-earth intellectual. Wechat official account: Xia Zi English class