When you use the game and get the arrived trains. Get the train that arrives at the station and close the game and double tap the home button and hold the monopoly app until it jiggles and shows the red cursor comes up, then push it. After that re-open and go to the station and get your cash or gold again and again.
Robber cheat
Catch the robber. As soon as you have click off the game then click back on and he will be there again. Keep doing this and you should get roughly 1000 dollars every 10 minutes.
Thimble room cheat
Fill all your hotels with thimble rooms as you recieve 125 dollars every 45 mins the rooms are very small I have roughly 58 thimble rooms and I get roughly 10,000 every 45 minutes.
XP
When on a 'level' your score shows and below your score is the number of points you need to reach the NEXT level. A good strategy is go for rooms that have high XP points vs high cash value.