Successfully complete a task that rewards you with a lot of money. Save the game 
if it is not at an auto-save area. Exit out to the main menu. Then, load the 
game to get the reward again. Repeat this as many times as desired.
In Chapter 6, find the pool on a hotel roof. Jump in the pool and swim around to 
have Chloe and Nate play a game of Marco Polo and get $10,000.