A lot of the way experts think is actually very domain-specific. So if you want to be good at thinking about a specific domain, might be worth reading one of Gary Klein's books about naturalistic decision making. https://www.amazon.com/Power-Intuition-Feelings-Better-Decis... is the most practical of the ones I've read.

More generically: learn how to write. Most hard problems won't fit in your head. Most of the ways we think are too vague and fuzzy. Writing things down and working through something in writing can help find the limits of your thinking process, and help you find solutions. I review a book that explains this very well here: https://codewithoutrules.com/2016/06/15/writing-book/

(You could alternatively take a good academic writing class at your local university.)

I'd suggest learning more about how to learn better, so that you can learn more on the job. Then you can spend your weekend doing something other than coding. Some useful books:

"How Learning Works" (I review it here: https://codewithoutrules.com/2016/03/19/how-learning-works/)

"Peak" https://www.amazon.com/Peak-Secrets-New-Science-Expertise/dp...

Gar Klein's books, in particular "The Power of Intuition" https://www.amazon.com/Power-Intuition-Feelings-Better-Decis...