Just a couple observations:
1. Try to avoid danger at all costs. That is your first line of defense. Avoid dangerous situations, dark parks/alleys, suspicious people.
2. Try not to stereotype "shady people." Honestly, you would seem pretty shady. If I was driving by this park and saw your vehicle with you drawing your gun on people and ordering them around, I would seriously consider drawing on you.
3. Rather than thinking of, "When can I draw my gun?" divert your thoughts to, "What actions can I take before I absolutely have to draw my gun?" These are things like retreat, diplomacy, etc.
Don't worry about when to draw, but what your options are before drawing. Once all of those options are exhausted, you may only have one option left: Defending yourself or another with deadly force.
May it never happen.