[header] How to not be rude [title] Think before you speak. [step] So many social errors could be avoided if only more thought were involved. A truly gifted conversationalist will always try to filter what he says before he finally says it. 
While thinking about everything you're going to say may sound exhausting to some, it doesn't require a lot of brainpower. Really, all you'll usually need is a split-second to figure whether something you say might negatively affect someone around you.