Ask HN: Getting software skills when you have almost no time

I'm working as a data engineer and I realized I lack some skills when interviewing for a new job: design patterns, good practices, object oriented design, query optimizations...

On my job I'm very deep into SQL queries, so it's difficult for me to learn those kind of skills on the job. So I'm feeling stuck.

I'd like to make some courses and read some books in order to brush up on that kind of skills but between my full time job and my one year child I've almost no free time to spend learning.

So I'm looking to optimize my learning path, finding myself on a paralysis of choice: I don't know if the best would be to start reading books, getting through a series of online courses or practice by reading OS code. It'd be great to learn those skills on an incremental way, a bit of every skill for each iteration.

What would you recommend?