Build Strategically
The easiest way to make money quickly in "Millionaire City" is to surround your businesses with houses on all sides. If you build businesses away from residential areas, none of your city inhabitants will frequent those businesses, and you will not earn any money from them. Since earning money is the key to advancing in "Millionaire City," you have to ensure that your stores and restaurants receive as much business as possible.
Build Big
You should also choose your building types strategically. While they may be more expensive in the long run, choosing contracts that allow more tenants per building will pay off fairly quickly. To maximize the earning potential of your businesses, surround them by the largest houses and sign contracts with athletes or pilots to allow the maximum amount of tenants.
Utilize Decorations
Once you build houses and businesses in your city, take advantage of decorations to increase your cash flow. These decorations don't take up as much space as the large properties, and they can provide a solid return on your investment. By simply adding a few trees to each house's yard, you can increase that home's profitability by at least 10 percent. Utilize every inch of space in your city by filling in small and odd-shaped areas with decorations. Empty lots make no money, so you lose money every minute they remain bare.
Help Your Friends
While you're waiting for your own city to grow and accrue money, spend some time each day helping out neighboring cities. You will walk away from each city with some additional experience points and cash. Be sure to take advantage of your Facebook wall, too. When you're prompted to post requests for help and items, choose to post these requests. Most fellow "Millionaire City" friends are happy to help out a friend in need.