Best Way to Learn Chinese?

As someone who has very casually self-studied Chinese over the past 6-7 years and gotten to an "intermediate plateau" (started as a digital nomad in PCR, then Taiwan, and then married my Taiwanese wife).

Since you've already learned many languages I'm assuming you are already familiar with what works for you -- for me I really resonated with the "fluent in 3 months approach" of basically just forcing yourself to consume as much content and use as much of it as you can (which I was able to do in Taiwan, starting with ordering coffee and working your way past the "where are you from" conversations).

I've always struggled with Chinese characters, however (I also struggled quite a bit with English spelling). I picked up https://www.outlier-linguistics.com/products/how-to-learn-ch... over black friday and have really been enjoying it. I'm not sure if it will resonate as much for a complete beginner, but with my limited experience it's actually making characters "make sense" for me.

ChinesePod has been fantastic for listening comprehension, and is also highly recommended.

Why do you want to learn Chinese? Your goals inform a lot of the advice. If you desire to work with the PRC, then learning Chinese in Taiwan, which is a very comfortable country for a westerner, will probably greatly harm your prospects and literally put you in harms way if you go to China. People I have met have first hand told me of threats to revoke visas (trapping a person in China) and literally imprisonment for saying the wrong thing, requiring action from the US State department. That was before China went full fascism on Hong Kong.

My low quality advice from someone who has done minimal research but who also has a desire to learn Chinese:

Go to Taiwan and take classes. Learn traditional Mandarin in Taiwan.

Why should you take classes even though you don't want to? Chinese is tonal which is completely different from the languages you already know. I don't know how you will get tonal feedback, training, or practice without classes. The writing system is different than the languages you already know and will likely require different strategies to learn as well.

Additionally Taiwan frequently uses bopomofo rather than pinyin. I am convinced (not through first hand experience) that it is better to attach meaning to completely new symbols rather than bring in legacy phonetic associations from the western alphabets.

The US state department defines Chinese languages as category 4, meaning they expect learning it, on average, to take on the order of 2 years of 30 hour weeks to become business proficient and that is with traditional training.

As far as culture and literature, when I asked a similar question to a well educated Chinese person, they suggested the four classic Chinese novels (https://en.wikipedia.org/wiki/Classic_Chinese_Novels) and specifically said romance of the three kingdoms has become a somewhat apocryphal history of China.

I understand it used to be traditional to start with https://en.wikipedia.org/wiki/Three_Character_Classic , which looks as if it offers plenty of opportunities to dive into cultural references.

A former coworker (Chinese) said "Chinese girlfriend? Six months. Alone? Two years." That was ten years ago.

It might be helpful to know if you want to specifically learn Mandarin Chinese, or another dialect (like Cantonese).

If you had a six-figure job, would you bother getting a college diploma?

Similarly if you had a Chinese girlfriend, would you bother studying Mandarin?

Be honest with what you really want before wasting time.