Starting as a small company with low balance, you have to reach the top of all companies. After picking your first product to create you will have to look for industries that will provide you with the needed resources. From there you have to plan out your production chain, which will mostly involve at least two industries, where you will have to refine resources and produce your selected product. This Product can now be sold in a store, which you have to build in a town. All these points will have to be linked with each other with one of the four transportation types. Then after starting the transport you will start to produce and deliver your wares to your store where it will be sold.
A complex economy that is able to detect each sold product and each bought resource will balance prices for every product or resource. And a system that allows the random creation of economy lows and high to make the game even more interesting. Try to create even more complex products to be able to gain more profit.