To ensure your city's survival you need to make sure that you have regular resources and food delivers. All of them have a certain purpose and have an impact on the entire city. If you neglect getting them you can be in real trouble.
Each of the resources are gathered from piles. In the beginning you only have access to basic piless that have a small number of resources that you can gather. You don't have to place anything on them. You just have to click on them and assign workers. Usually, those piless are depleted within a few days. Because of that when you build a workshop you must first focus on unlocking buildings that can allow you to get resources from other places. Depending on a place in which you build them they have a certain amount of resources to gather. They are rather big numbers which means that you won't have to worry about finding new piles soon. In addition to that they can also generate more resources per hour by having less workers.
Coal is definitely the most important resource. It powers a reactor. A reactor uses a certain amount of coal per hour. Of course, you must remember that you can't gather coal all day and night. For example, if you use 9 units of coal per hour then you need to gather at least 22 units per hour if you want to have your reactor running 24 hours without a stop. This means that you need to control how much coal you have. Especially when you upgraded your reactor and/or build a new source of heat. This causes greater usage of coal per hour. If you won't modify the number of gathered coal you might not have enough of it for a night.
Wood is another resource available in the game. It is used for creating all buildings in a city. It also allows you to conduct researches. How you get it depends on you. You can get certain amount that you currently need or you can get it in bigger numbers and store the excess in Resource Depot or Gathering Post. Remember to unlock a Sawmill. There may be a situation in which you got carried away and used all basic depots and you don't have wood for researches/buildings. When this happens the only option left for you is to destroy a building and get wood from it.
Metal is a resource of which demand rises over time. In the beginning of the game it is practically useless. That is why you should keep its extraction at a low level. However, with your development in researches and unlocking new buildings this resource starts to be really necessary. When that happens you should increase its extraction rate.
In order to help your city survive you will also need food. Hunters are the ones that can gather it. They go outside your city's terrains to hunt. This process takes some time because you need to wait 24 hours to get 15 units of raw food. In addition to that, your hunters need to rest after each hunt which makes this time even longer. In the beginning, one Hunter's Hut is enough, however, after 4-5 days this amount won't be enough which is why you will have to build another one.
Hunter's Huts get you raw food which must be later prepared in kitchen. Only after that it can be given to your citizens. For gathering food you can use "Soup" law but you can also use "Care House" law. Terminally ill dwellers are placed there and thanks to that they eat less food.