There are different ways of earning income besides the legal businesses.
You can deal with alcohol: Moonshiner, Beer, Champagne and Canadian Whisky.
The yellow neighborhoods – New Jersey, Southwest Queens, Rockaway, Long Island City
It is up to you to decide in which neighborhood you would like to see varying deals happen. You are completely free to choose.
If you freed or conquered one of those neighborhoods, by clicking on it or on the map, you will be able to select alcohol by clicking on the money symbol (Prohibition) in the left menu.
Here you will be able to manage every feature of your alcohol businesses. Expand buildings, transport and selling of alcohol, as well as getting an overview over past activities. On the left side of the menu you can easily navigate to the different wares.
To turn alcohol into wealth, you need an inconspicuous shop were you can sell all your products.