When talking to the cabin: slow down, take your time, avoid jargon, think about what your words will convey, and speak "human."
Just like the Irish pilot of the Beverley said via the PA to the 50 or so Army personnel cooped up in the boom, acutely aware of the fact that we had already had 2 attempts to take off at Bahrain on a hot day,
"OK then, this is our last try. We'll get off if its the last thing we do."
The Beverley boom could be quite a smelly place.