Don’t use quotation marks when nothing is being quoted. If you want to emphasise a specific part of the text, use italics.
Any orders ‘over £500’ will receive a 10% discount.- Any orders over £500 will receive a 10% discount.
The title of his latest film is ‘The Ring of Fire.’- The title of his latest film is The Ring of Fire.
(Using capital letters shows it is the title of something.) - The title of his latest film is The Ring of Fire.
(You can use italics for extra clarity if you wish.)
