When your playing the game either a fire or tornando ect.... Pops up and you have to pay your way out or loose crops money ect... Just hit your home key to exit game and clear your cache and end all processes (I use task killer) to end all. Then when you go back into game the disasters are gone and you never loose anything.
Find the post situated at each fort and start the mini-game and intentionally lose just before it ends. Select 'No' when you are then prompted to play again for a bonus. You will now be returned to the fort with $1 for each correct tap you had previously made. Keep repeating the process until you have the desired amount of money.