When you get the option of going into the Senate, click the "Emperor" icon in the Senate. Give yourself a wage of 500 Denarii (Caesar's wage). After you accumulate about 3000 Denarii, go to the same screen and select the "Give To City" icon. Click the "All" button in the dialog. Then, press the "Give" button. Notice that you now have no savings at all. Press the "Give To City" button again. Do not press the "All" button again. Just press the "Give" button again, and your savings will have a negative value. Repeat this to gain a fortune. You can turn off the Senate screen and return to it later to give yourself more money.