"If you are an American, using quotation marks could hardly be simpler: Use double quotation marks at all times unless quoting something within a quotation, when you use single. It's different in the greater Anglosphere, where they generally use singles in books and doubles in newspapers."
I was educated in the UK over the past six years, and Australia two years before that, and as far as I know, single quotation marks are used for conversational dialogue.
Please excuse the difference and I may be able to do a mass edit of the quotation marks in the future!