Think through completely what you are about to say before you say it.
Case in point. Today while outside doing the firewood for the fire tonight (winter here) I spied a large package addressed to my wife. One of her horsey parcels obviously. But what I said wasn't exceedingly bright.... I said ' That's a very large box you have there', but to make matters worse she was the one chopping some of the kindling at the time and was standing there with a 3.5lb axe in her hand when I said this.