Ask HN: As a person, what can I do to improve a city?

I live in a "Top 10 most dangerous cities in the U.S." What can I do to help? It seems like the most common solution for people who are educated and well off is to move. To get out of the situation, which is understandable. However, this causes a brain drain and leave the city in a worse place.

I don't want to do that, I want to uplift if I can. What is the micro thing I can do today, that can have a chance of a macro change tomorrow?