Season fish however you like. Preheat pan to med/low - med. (can't emphasize that enough, most people crank the dial way up there). When you can feel warmth just holding your hand 4-6 inches above the pan coat the bottom with about a tablesppon of olive oil and swirl to coat.
Put fish in pan and let go for about 2 - 3 minutes for an average fillet, and as much as 3 - 4 for steaks, turn over and repeat.
This is my favorite way to eat fish and it works with most anything as long as you season accordingly (mahi mahi, tilapia, salmon, trout, grouper, etc.)