People who read this blog, as well as those unfortunate enough to know me, will be aware that I don't have a PhD in English. The latter will know and the former might have noticed that I'm just as interested in medieval history and 1970s German rock bands, although the jury is out over which subject bores them more. That's a long-winded way of saying that there are people far more qualified than me to write about what is strictly correct in language. I'm more interested in clarity, and that includes breaking the rules and even making new rules.
If you're a stickler for the rules, then the correct way to write an abbreviation is with dots between the capitals. At every publication where I've worked, I have vigorously campaigned to get rid of these. As far as I'm concerned, dots have two functions: as full stops (periods) or decimal points. I make two exceptions: e.g. and i.e.
The final dot can cause confusion if it comes at the end of a clause but not at the end of a sentence, and the problem is worse if the dot comes at the end of a line or a page. If you insist on keeping the dots, then you're on the slippery slope towards insisting that all acronyms should be in capitals, and from there it's only a short step to insisting that radar be spelt RaDAR. It's already obvious that UK, USA and SPLAJ* are abbreviations. What purpose do the dots serve? Lose them.
Do they says that?
Boy, do some people get upset about 'they' as a non-gendered singular pronoun. It's been used like that since the 14th Century. More importantly, it gets writers out of having to write horribly awkward sentences full of 'he or she'. If you really want to get into it, Motivated Grammar has written a long blog post about it so I don't have to. Drink it up.
Elisions are wrong in written English
No they aren't. The more formal your writing, the less you should use them. That's all.
Brackets (parentheses) are ugly
Brackets are viewed with distaste in some quarters, while en- or en-dashes provoke horror. It's true that the dashes are over-used and brackets are under-used, but both are a useful way of making sure sentences with conditional clauses don't get overloaded with commas.
If you find your prose needs brackets, then it's possible that your sentence is over-long and too complex. See if you can break it up. If you can't, then the en-dash and the bracket are your friends.
Americanisms are vulgar
Like most Britons my age (I turned 47 last week), I was brought up surrounded by prejudices against the Americans and the Germans. Both are beautiful countries with lovely people, and have contributed more than most to the world's cultural and intellectual progress. America has driven the development of the English language over the past 80-odd years and we would all be a lot poorer without its contribution.
A recent BBC article displayed how this prejudice blinds us. In a list of hated "Americanisms" were plenty of appalling expressions that have nothing to do with the USA. People see words and phrases they don't like and instinctively blame them on America, which says more about their own narrow-mindedness.
Every country and region has its own variety of English, and some idioms belong in one place but not another. You can't blame America if an Englishman is foolish enough to say a cricketer "stepped up to the plate" (and yes, I have seen it). Sloppiness of thought and speech deserves to be derided, wherever it comes from. If an expression is fresh, vibrant and appropriate then you should use it, regardless of where it came from.
To boldly split infinitives no one has split before
Back when some of Britain's more pompous imperialists were trying to equate the British Empire with the Roman, Latin was held in high regard. Since Latin infinitives were single words, they couldn't be split, so it was felt that English infinitives shouldn't be split either.
That's a load of twaddle. The Latin verb ire (to go) is never split, but neither is eo (I go). Generally, it's bad style to put anything between the verb and its subject, and the same goes for the infinitive. It's just ugly, not wrong. If it makes your sentence better, go ahead. "To go boldly" doesn't work as well as "to boldly go". Gene Roddenberry's honour is intact.
Anyone who cares about clear writing either knows Orwell's article Politics and the English Language off by heart, or can't wait to click this link and wonder why it took them so long to read it.
Moral: Break any of these rules sooner than say something barbarous (George Orwell).
*Socialist People's Libyan Arab Jamahiriya, though Libya probably won't be called that for much longer.