Most writers will eventually stumble upon a punctuation enigma: quotation marks. As per standard American usage, always use double quotation marks when setting off a single word, title, or phrase. The only time you use single quotation marks are when you are quoting within a quotation: The woman said, "I am what many people call a 'foodie.'" Quotation marks are suitable for irony, titles of artistic works, nicknames, but not for emphasis. To create emphasis, italicize the word.
The other important thing to understand about quotation marks is how to punctuate. Periods and commas belong inside the end quotation mark. For example: Last night, I went to see "Ocean's 13." A question mark goes inside the end quotation mark if the subject being quoted is a question. For example: The man asked, "Why do I need to know about punctuation?" The question mark belongs outside the end quotation mark if the quoted material is part of a question. For example: What did you think of last night's episode of "The Sopranos"?
Generally speaking, quotation mark usage in the UK is the opposite.