For specialty interests, pick one at a time.

Start by picking up an intro book on the topic and reading it.

Ideally then find a community that discusses that topic and start researching the questions people ask and try to formulate answers.

This will both have you learn piggybacking on others’ curiosity, as well as invoke Cunningham’s Law for anything you get wrong in your answers.

As you immerse yourself, you might pick up other books or things you’ll want to read to understand more too.

After a little while, you’ll be much more well versed in the topic.