I'll propose a couple more: 1. If someone mentions having just returned from country X, do not take this as an invitation to launch into extended monologue on

I'll propose a couple more: 1. If someone mentions having just returned from country X, do not take this as an invitation to launch into extended monologue on your trip to country Y of ten years ago. 2. Do not ask people what they "do" -- to a shift worker of low-level service jobs, it yanks the mind's attention back to recent humiliations inflicted by rude customers or oppressive managers. Similarly any other question that might be heard as an attempt to gauge social status. You will see these faux pas a lot -- the trick is to not fall into them yourself.