The first step is realize that you may be in a reactive situation, and then monitor yourself as much as the other person for reactivity. Not all 'altercations' need to be out of control; either way, remaining calm (genuinely calm, not 'white knuckle calm') improves the chances of a successful resolution, while reactivity only escalates and guarantees greater problems. Most people pay waaay too much attention to the other person and designing their own attack rather than reserving attention to their own state of mind/emotion.
Just like the martial artist in the movies who is surrounded by a dozen bad guys, and beats them all, the implication is that he won because he had greater control of his own emotion, and is responsive instead of reactive. Learning how to 'differentiate' in charged situations not only helps you manage them better, but leaves with far less distance to 'calm down' from.