Some self defense
instructors recommend that you keep this in mind
if ever you are faced with a potentially lethal encounter. While it probably is taught in the spirit of common sense
it can also get you killed
Some people hold the idea that guns are not deterrent devices and should not be used as such, that is, only use guns for what it was designed for, which is killing people, not scaring them.
While nine times out of ten it probably is the case that by drawing a weapon you would have needlessly escalated the situation and would therefore be at fault for any outcome, there are instances when a show of implicit force, by pointing a gun for example, is enough to stop an attack. If you find yourself in such a situation, you should by all means restrain yourself from firing if the threat is gone, if for example your attacker retreats or begs for his life, you should try to withdraw from the encounter but still with utmost caution. A withdrawing attacker that still spouts threats of revenge and threats of "calling his homies" is still retreating and should no longer be treated as a threat.
When I earlier mentioned that the thought of only drawing a weapon to fire could get you killed can be interpreted two ways, one, that by delaying your decision to draw your would be attacker might gain the upper hand and whack you before you ever had a chance, or two, by making the decision to fire even before drawing, you might find yourself in court being charged and convicted of a homicide that you will not be able to justify.
As always, the use of lethal force is not to be taken lightly and it is with utmost judiciousness that one must conduct oneself if one is allowed the right or privilege for armed self defense.