The quickest way to lose a large fish is to try winding in slack line while the fish is escaping. If the fish is very large or fast, allow it to pull out all slack. If the fish stops its run, either move away from the fish, or use the boat to clear slack line. Once all slack line is gone, you fight the fish on the reel. Time and again, I have seen people so distracted winding in slack that they lose fish. Of course, if the fish is small, simply bring it in using the line hand.