Are you aware that almost every day you see one or more signs using quotation marks improperly?
“In business since 1979”
“Apple pie like your mom used to make”
“Call us for affordable repairs!”
No one ever said these things. They were made up to call attention to what the advertisers want you to remember.
Legitimate uses of quotation marks are when you are quoting the actual words someone else either said or wrote, or when you use a word knowing that your readers are aware you are being facetious or sarcastic.
For instance, if you write that your Aunt Edna is on a “strict” diet and then you go on to write that she eats strictly high-calorie foods, your readers understand your sarcasm. But in the last sign listed above, putting quotation marks around “free” seems to indicate that the delivery is, in fact, not free. It’s as if the company is poking you in the ribs and saying, “Ha! Not really.”
If you want to call attention to certain words, instead of quotation marks, you can use italics or boldface type. But please do this very sparingly.