What is the best way to learn Cantonese?

Watch Cantonese TV \ movies first, at least listen to some of them first. (This is very easy, it is best to cover the subtitles and get a general understanding. )

Then listen and learn to sing Cantonese songs. At the same time, when watching Cantonese TV \ movies, you can say the reflected lines in your head first. If you are wrong, don't be afraid to see if what you think is the same (or similar) as what others say. This method can also be used to learn English.

I usually look for some newspapers and see if I can read them in Cantonese.

Finally, the key is to find some people who can speak Cantonese to talk to you. This step is to practice oral fluency.

There are many "local dialects" in various places, so this new scholar doesn't have to be too strict with himself.

That's about it. That's how I learned Cantonese.

In Hong Kong, no one I contacted recognized that I was not from Guangdong. Everyone thinks I am from Guangzhou and Shenzhen, but I have never lived in Guangdong.