Second thoughts are ever wiser.

The first response comes from whatever you were feeling a second ago; the second one has the benefit of having seen the first. That is all the wisdom amounts to, a little distance and one pass of review, enough to catch most of what you would have regretted. The fastest reply is so often the worst because speed feels like decisiveness and is usually just the first draft escaping.

Build a delay in where your damage happens: the reply sent angry, the yes given too quickly, the purchase made standing up. Write it, decide it, then leave it until the next morning and see what the second look says.