Rule: Avoid using quotation marks for emphasis. Quotation marks enclose directly quoted speech or text. Do not use them to emphasize words or phrases. You may use quotation marks to call attention to an unusual or incorrect meaning of a word. Sometimes, in fact, the use of quotation marks implies that the word is being used ironically or humorously with the opposite of its normal meaning. This last use of quotation marks is sometimes called "air quotes."
Examples:
Wrong: "Close the door" after you leave the barn.
Correct: Pat suggested that I "close the door" on my old way of life.
Wrong: Please "do not" put gum under your seat.
Correct: My parents teased me about my "study" habits when they found out how much time I spent watching Netflix.
Correct: Everything the politician told us was "true."
Practice:
I insist that you "take care" of your younger siblings when your parents go out.
He was the "only" person in the room who understood why the quadratic formula works.
They kept saying they "needed" to have that new book when what they meant was that they "wanted" it.
Employees must "wash hands" before returning to work.
Resources:
Language Humanities's explanation of air quotes.
Merriam-Webster's explanation of air quotes.