Punctuation is an essential tool of the trade for writers, and in the UK we seem particularly ignorant about inverted commas. They're even taught incorrectly in schools. I'm not referring to the punctuation mark that shares the same symbol - the apostrophe - but inverted commas, a.k.a. speech marks, quote marks or quotation marks.
There are three regular misuses. One is the idea that there is somehow a difference between speech marks and inverted commas used to isolate something, perhaps something 'dubious.' No - same rules apply to both.
The second problem is overuse of inverted commas to indicate 'terms' that we aren't really 'comfortable' with. If you find yourself doing this, go back and put in terms you are comfortable with. Using inverted commas in this way is amateurish.
Finally, and this is the one schools get wrong, there is the convention on when to use single inverted commas and when to use double. In the UK the convention is to use single pairs of inverted commas, then double ones if you need more inverted commas inside that first set. For example you might write:
'I just heard Mary say "I'm fed up," but she's not really,' said Peter.
In the US the convention is the opposite - double for first use, single for ones inside the first set.
For some reason, British schools teach students to use double inverted commas first - but the convention is very clear and you will find it in any UK writing style guide. Take a look in practically any book published in the UK and you will see it done this way. (Newspapers and magazines aren't such a good guide as they often go their own way on style.) So please, please, British teachers stop getting it wrong!
Several times I've pointed this out in my children's schools, but just got blank looks. Sigh.