Writing is awash in conventions: Start a sentence with a capital letter. End a sentence with a period, question mark, or exclamation point. Don't hyphenate after an adverb that ends in "-ly." And on and on.
All that stuff is my stock-in-trade. So I was delighted to discover (by way of reader Joel Blum, of Paris -- thanks, Joel!) that comic-book letterers have their conventions too: Point the balloon tail at the character's mouth. Use burst balloons only for screaming. Use hollow sound effects when you need impact but have serious space constraints.
If I hadn't read all the way to the end of Nate Piekos's "Comics Grammar and Tradition" page, I would have missed wonderful information like "Old-school telepathy balloons look like a thought balloon except they have breath marks on opposing corners" and "Traditionally, whispered dialogue is indicated by a balloon with a dashed stroke. More recently accepted options are ..."
An irresistible time-waster.