Things I found that make money fast

• Contracts: Doing Contracts at 5 stars makes over 2 million per month. The most effective way is having split teams of developers, artists and designers.
• Stock Trading: If you have $1 billion to invest, you can make a few free million over a month by just investing in the stock market and doing nothing else. (you can also lose if you make the wrong investments)

Teams

I have 3 sets of teams for each "team" i.e for core i will have Core (A), Core (B) and Core (C) who will work around the clock. So basically for every team you have make other 2 identical teams to work the after hours. 3 teams because each team works 8 hours and a day has 24 hours.