If you succeed in building a successful city, you are granted in increase in rank and given another city to build. Each time you start a new city you may choose between two locations with different challenges. Building a successful city depends on your ability to supply food and water to your people, manufacture and trade goods with neighboring cities, entertain your citizens and maintain their health, appease the gods, and defend your city from enemy attacks. The only rating category that I found difficult to master was prosperity. The other ratings increase automatically as long as you defend the city, send oil to Caesar when he asks for it, and entertain your people.
Prosperity is a little trickier since it depends on several things.
See the hints section for my advice on increasing the various ratings. You may view this file here . A sharp threshold exists for keeping the gods happy or making them angry. For example, you can build 3 temples to Ceres in a large city and she will continue to be angry. But, if you build one more temple she is suddenly indifferent.