Focus.
When your in a fight your mind goes a 100 mile per hour, if you can control, this, you can control the fight, otherwise it will end up being a fight with both or 1 person throwing whatever they can and get tired asap.
If you Focus and stay calm, you save alot of energy and alot of missed punches (or kicks or butts or whatever).
Remember when you are close make use of your elbows and knees, you will be suprised at how much power you got there.