One thing I learned early in life was that when writing an initialism, you should first write out the fully expanded form of it, for the benefit of those who don’t know what the initials stand for, and then abbreviate it by the appropriate initials in parentheses (also known as “brackets”).
The same goes for the use of acronyms.
In most cases, the expanded forms are only necessary for first mention of what is being shortened, but there are some situations where it should be repeated later. (See the links I include at the end of this post for more on that.)
I cannot count how many times I’ve had to ask an internet writer what their initialism, abbreviation, or acronym stands for. Some of them are such popular groupings of letters that even looking them up on a search engine results in too many possibilities to pinpoint which one it is.
A recent one I saw was on a writer’s group. It was “ARCs”. Now, maybe that is something that makes sense to people who spend oodles of time on that forum, but for me who only pops in once every several months to ask a question or look something up, I’m lost. Hopefully, it’s not important, but it does make me wonder. Especially in a writer’s group, you’d think they would pay mind to some basic rules of English writing.
For more information on this topic, here ere are a couple of links I enjoyed:
PS: I got an answer on what ARCs are: “advance reader copies”, in reference to book publication.