Just beat it. There is not much to tell you but to always keep up on watering the plants and giving people the keys to their rooms. Never, ever fall behind on these things, because if the plants aren't watered, everyone gets impatient faster and you lose money. If a person at the desk or someone in line leaves you lose all the the money they may have spent.

If you aren't serving 30 people in level 50, you aren't keeping up and you won't earn enough to win.