Please give me some advice.

No, watching films is generally not a good way to learn English. Many films have slang dialogue or it's hard to hear what people are saying, either due to the soundtrack or other action going on. You will do better to watch television, which tends to move a bit more slowly and quietly.

Yeah, especially don't watch Billy Madison, otherwise you will be walking around saying "Tally-hoo-hooo" and thinking you are saying something.

Some excellent English can be heard in the BBC TV series of Pride and Prejudice starring Jennifer Ehle and Colin Firth and you can read the novel on the side, for it is very true to the story and many of the dialogues are taken literally from the book.

In general filmatisations of literature is your best bet, because they allow you to combine the written and spoken word with images.