It is really pretty simple.
Only draw your firearm if there is no other way of protecting your, or someone elses, life.
If you can run from danger, run. If you can drive from danger, drive. If you have time to call 911, dial. If you can protect your life with your fists, fight, don't draw. Any other useage is questionable in the courts. (as George Zimmerman has discovered; even in a state with one of the most firearm friendly laws)
If you draw your gun in a dispute you may be forced to prove that your actions were "reasonable", a test that may be decided by a jury, and juries can do strange things. Even if a jury decides that you were "reasonable", it will have cost you a fortune to defend yourself.