What are two key points in dealing with an aggressor? Based on personal experience, interviews and training I would say;
1. SHOW NO FEAR! Inside you may be quivering like jello, but outside stay cool. Easy to say, hard to do, but it you prepare yourself before it happens you are better off. Catch him or her off guard with a strong voice and response.
2. GET OFF THE X! This means MOVE! If someone is charging toward you, move to the side, move to cover, get out of the way. Think Matador not Tight Rope. Once you are off the X, keep moving.
Of course there may be a situation where you need to stay and fight, but it is always preferable to get away and live to fight another day. If you must fight, the only rule is NEVER GIVE UP! Show the cretin the same mercy they are showing you. Do not be squeamish, or worry about causing injury. You believe you are fighting for your life and your body. Go for the tender areas, the eyes, the groin. You are fighting to stop the threat. If that means a physical response, employing a weapon, or shooting them; you do what it takes to stop the threat. Once the threat is over, get to safety and call the police.
Be alert, be aware and be safe!