It seems like some of you are afraid to fight and think shooting someone to avoid a fight will be ok.
The fact is that if they are unarmed and you shoot them, you'll most likely lose in court and end up in prison. About the only time you'd be able to justify killing someone is if they pulled a weapon, or if they were quite a bit larger and presented a huge threat. If you weighed 120 pounds and a 300 pound football player lookign guy came at you, then deadly force would definately be a good option. But if you were of equal size as the unarmed bad guy, then you'd have a fight on your hands in court.
Yes pulling the gun to stop him from advancing would be wise, but what if he keeps coming at you? Would you be willing to kill an unarmed man and try to convince a jury that you were right?
BreacherUp! is on the right track. Learn to fight without a gun before you bother carrying a gun.
Here in NM, open carry is legal. So I doubt that letting the guy know you are packing by just casually uncovering the gun would be any problem for you at all.