Larry Arnold explained the best way to win a gunfight!!
The number one best thing anyone can do is not get into the gunfight in first place.
Even if you win you risk having someone you care about getting hurt. Or anyone else for that matter. There are also repercussions if you do shot someone. Was it self defense
Did you have to use deadly force? You may have to go to court for a long process to prove you were right. Of course if you loose your case you could go to jail. Walking away is always the best option.
 If you can't get out of it then use your head. Cheat get your gun ready to go before the other guy. Don't play like your in the movies, this only gets you killed. Look for any advantage. Get behind cover.
 Make yourself a more difficult target in order to engage from a position of tactical advantage. If you stand still, there is much greater chance that you will have holes poked in places that don't really need holes.
  Common sense plays a large factor in winning. If you can't draw and shoot fast then get practice until you have a better speed of drawing and shooting.