In order to succeed in this game, you must be knowledgeable in business economics, political science and war tactics. To improve infrastructure, first you must try to improve health, education and transportation. Good health care and good social security will bring your population up. Build a few corporations in the beginning so that the majority of your population is employed.
The best thing to do first is grow your population so that you can build more corporation. Another way to grow population is to pay for membership. 1M pop = 5C. When you have a lot of people who can work, your country can support a good number of corporations, which means a high employment rate. High employment rate of a huge population is good for your economy because of tax and circulation of funds throughout your country. Trade with other countries to gain more capital.