One of the foundations of writing is issues that aren’t grammar per se, and usually aren’t punctuation or even getting the facts straight, although those things are all really important. Rather, it’s issues of style.
I don’t mean flair or that certain je ne sais quoi* that makes your writing irresistible. I mean the set of rules that you apply that relate to word choice or to how you treat numerals in text or what you capitalize and what you don’t.
These rules are largely arbitrary, and that makes it frustrating because you have to just remember them, or remember to look it up.
Even in my professor job, I have several different style systems to worry about. Wire service style is used in media writing, which I teach. My fancy research articles use either APA or Chicago style, depending on where they are published. These three have thick books describing all the rules.
Your writing life may well be simpler, but I have one tip to make your professional writing easier:
Write it down, and then do the same in the future.
Those lists of rules typically come from, hem, passionate discussions involving the people who work with the publisher of the writing. You don’t want to repeatedly have those arguments. So even if you are deciding that on your company intranet, you will say the conference room is the Conference Room (caps) or room 418 or Room 418, once you decide, write that down. As you do this, you get a list of local style, and you never need to have that fight again.
*Whether you would use words in a foreign language or, if you do, if you would italicize them? Style issue.