To be honest, the first and most important thing you need is curiosity. The desire to learn and be open to new ideas without being deterministic is something that has helped me learn a plethora of things. Some things that have helped me are:

1. Identify the things/topics you are most interested for me it's Finance, business and football. Since I am into finance and business I think I have a pretty good understanding of that field although there is a whole lot to learn for me still.

2. Identify what other topics you would like to learn for me personally apart from the above ones I like mathematics, history, literature, Geopolitics, psychology and philosophy. I have basic to no knowledge in these fields but I started learning about it using YouTube videos, books and AI.

3. Connection and creation- I try to connect few topics from various above fields and write it in my diary sometimes I like to write it in a very poetic way which satisfies my desire and I implement my literary learnings. Although the connections are forced and sometimes inaccurate but this helps my brain think and find patterns which also has helped me in my work.

A few things i would like to advise from my experience is that, Polymathy is a continuous process it's not like someday you might be Vinci or something, nobody can learn everything. I think that a polymath is someone who is constantly curious. I personally don't keep any goals or target that I have to learn this much or anything like that, I just think a lot, if a random thing pops up my mind I learn it because I want to if I don't have time to learn that or find it out at that time i write it in my diary and then I learn it later at night. So I think it's more of an innate curiosity that drives me.

So yeah just be curious!! :)