GET OUT OF THE CITIES NOW BEFORE ANYTHING HAPPENS !!!
Truely, your life is in your hands and nobody knows more about your situation than you. You are the most qualified person on your own personal preparedness. BUt here are some general guidelines:
If you are stuck in the city, stay down, stay quiet and do not advertise to everyone else that you have food and water. Be ready to evacuate your building in the event of fire or other problems. Have back-up locations inside the city... friends, family or neighbors. Have some form of firearm. If you can rig a way to collect rain run-off and charcoal filter it discretely, so much the better.
Really, it depends on the situation. We can offer options and specific preparations but ultimately you are incharge. Often the situation is too complex and too fluid for a flowchart of what actions to take and when. Is your city just experiencing local problems? Or is this a nation wide disaster? Is normalcy going to be restored soon? Or is this the big end? Are you in the position to help your elderly neighbors? Or is this a dog-eat-dog fight for survival? See what I mean? Too many factors for anyone but you to make the call.
I get these 5 gallon pickle buckets from Burger King for free. I use them in my greenhouse. You could easily store purified water in them for months at a time. In the city, water is most likely the most critical necessity. If you have no heat, get several neioghbors together in one house or apartment. People put out a lot of heat if you have enough of them in a small enough volume. Just plan ahead.