What to read / do to the automator at your leisure?

Question

Automation

Hello everyone, I quit a couple of months ago to resolve issues with the military registration and enlistment office, the last year and a half, in principle, passed first in my studies, then in work, I'm already tired of spitting on the ceiling. I worked as a tutor, but I don’t see prospects for myself in this. I'm going to jump in as a test automator in July/August, under good circumstances, so here it is:
My main stack:
Selenium
Databases
Java (main) / C #
It is clear that there is still room for improvement, but I'm still interested in what -things that, in your opinion, are worth studying now and which will give an additional plus, preferably within the framework of test automation, of course.