"If you ever find yourself in a fair fight, you have fucked up."
"If you're fighting dirty, you're doing it wrong. You should be fighting in ways that make dirty look good by comparison."
I've also been partial to : "I believe in preemptive strikes and parting shots"
The best defense is to never let the other guy attack.
Now whether you do that by overwhelming force, overwhelming diplomacy, overwhelming deception, overwhelming stealth, or anything else is up to you. But if he never attacks, you win.