Fights only happen when other relationship systems have failed.

Over time, too many fights create excessive scar tissue, leaving a gnarled mess.

No. There is one fairly good reason for fighting — and that is, if the other man starts it. You see, wars are a wickedness, perhaps the greatest wickedness of a wicked species. They are so wicked that they must not be allowed. When you can be perfectly certain that the other man started them, then is time when you might have a sort of duty to stop him.

Fights between individuals, as well as governments and nations, invariably result from misunderstandings in the broadest interpretation of this term. Misunderstandings are always caused by the inability of appreciating one another's point of view. This again is due to the ignorance of those concerned, not so much in their own, as in their mutual fields. The peril of a clash is aggravated by a more or less predominant sense of combativeness, posed by every human being. To resist this inherent fighting tendency the best way is to dispel ignorance of the doings of others by a systematic spread of general knowledge. With this object in view, it is most important to aid exchange of thought and intercourse.

If a person resolves to fight, he ought to know what he is fighting for. Otherwise it makes no sense. A person usually fights against a power in order to gain power himself. Or else because the power in question is threatening his life.

Being mean makes you stupid. That's why I hate fights. You never do your best work in a fight, because fights are not sufficiently general. Winning is always a function of the situation and the people involved. You don't win fights by thinking of big ideas but by thinking of tricks that work in one particular case. And yet fighting is just as much work as thinking about real problems.

It is not honourable to attack an enemy without putting yourself at risk.

Anywhere is dangerous if you carry danger with you.

Everyone that you fight is not your enemy and everyone who helps you is not your friend.

Without enemies around us, we grow lazy. An enemy at our heels sharpens our wits, keeping us focused and alert. It is sometimes better, then, to use enemies as enemies rather than transforming them into friends or allies.

You and I, we are fighting each other but we are not really enemies. By doing so we are dividing our strength, and we shall never reach our goal. Maybe the final extremity will bring us together. Maybe.

IF YOU ARE ABOUT TO BE IN A SWORDFIGHT
This comes up a lot and I am working on upgrading the relevant wiki pages, but people seem to end up here anyway LOL.
My basic advice: DON'T DO IT! It is ridiculously, fantastically dangerous. Modern people are calibrated for a whole different level of danger acceptance.

When your opponent fears you, then’s the moment when you give the fear its own rein, give it the time to work on him. Let it become terror. The terrified man fights himself. Eventually, he attacks in desperation. That is the most dangerous moment, but the terrified man can be trusted usually to make a fatal mistake. You are being trained here to detect these mistakes and use them.

He'd learned that the object of a school fight was not to gain points for style but to force your enemy to give in, which meant hurting him more than he was hurting you. He knew that you had to be willing to hurt someone else, too, and he'd found out that not many people were, when it came to it; but he knew that he was. So this wasn't unfamiliar to him, but he hadn't fought against a nearly grown man armed with a knife before, and at all costs he must keep the man from picking it up now that he'd dropped it.

Never pick a fight with someone you're not sure you can defeat.