Everyone needs a Bible, and for many journalists and PR pros, that's the AP Style Book. The Associated Press has produced this valuable guide since before I was in college.
Now in an online, easily searchable format, the stylebook tells you everything you need to know about what you should capitalize and when. It goes into how to use organizations' names and has FAQs, and if they don't answer your question there, an editor will. It also grants permission, somewhat grudgingly, to make grammatical changes, such as using "over" instead of "more than." I'm waiting for "like" to be endorsed so I can drop "such as."
I can't tell you how excited I was when AP blessed the use of "they" instead of the cumbersome "he or she" a couple of years ago.
Plus they keep up with the latest trends. Did you know that you're supposed to capitalize Black when writing about Black people, but not the w in white?
Here's a brief story explaining the latest ways to talk about COVID-19. AP says it's OK to refer to it as the coronavirus on the first reference in an article — even if though that's inaccurate because there are numerous coronaviruses. Sometimes if you misuse words long enough they get accepted into the lexicon.