In my experience, there are two modes to learn accessibility:
- Learn from within
- Learn from afar
Learning from within means getting your hands dirty. You actually fire up a screen reader and try to navigate your own website. You unplug your mouse and try to do it with just your keyboard. That's when you get hit with all those little frustrations and roadblocks that users with disabilities face every day.
Since doing requires that you actually do something, learning from within stops you from overthinking things.
Learning from afar on the other hand gives you the big picture and helps you understand some of the "why" in web accessibility. You do it through reading articles, watching videos, however you're comfortable amassing information.
They both require you to be curious and open. Neither is wrong, but only one of the two results in better learning outcomes.
The best is probably a mix of the two, with an emphasis on hands-on experience. You're also likely to move from one mode to another constantly.
Just be sure to not get stuck absorbing information without applying it. Don't overthink things.