I found an article with a great overview of urban survival skills. What makes it interesting is that it looks at urban survival from three different perspectives: The Stockpiler, The MacGyver, and The Survivalist.
For example, when it comes to food: the stockpiler needs to know how to store it, the Macgyver needs to know how to cook meals with almost anything, and the Survivalist needs to know how to make meals out of food from garbage cans. Ideally, you should know how to do all three of these.
The post covers safety skills, natural disasters, finding shelter, purifying water, cooking food, and signalling for rescue. It’s full of links to great resources and instructional videos. I recommend bookmarking it so you can read it again.