Go directly to the island from the boat at the port with 10,100 Simoleons remaining. Go by the bay side until you see a blonde rich girl named Elizabeth. If you make her happy, she will ask if you would like to buy a house. Buy the house. The house has a pool, three rooms, a gate, and a big flower bed. She will tell you more about her and become a best friend.
To get infinite money, get 10 Coins, then go to the Tic Tac Trump game at the casino. Bet 6 Coins. Do not double, then lose. The game will still allow you to bet 6 Coins even though you only have 4 Coins. Bet 6 Coins, and lose. The game will list your amount of Coins as -2. Quit Tic Tac Trump, then choose to play it again. Bet any amount, and win. You will have 9,999,999 Coins.
To win Elizabeth's Fashion Review, you must have the following outfits on your Sim:
REVIEW - OUTFIT Entertainment Area - Silver and blue custom top with red pants/trousers. Forest - Green and brown custom top with brown pants/trousers. Highlands - Purple and pink custom shirt with black roll-up pants. Mountains - Orange custom top with green pants/trousers. Port Area - Custom top of blue shades with light blue jeans. Town - Red and black custom top with blue jeans.
To easily earn money, go to the Entertainment Area, and catch a fish called an Anomalocarid. Give it to Joseph, and he will almost have a heart attack from how big and mean it is. Joseph will pay around $1,200 for it.
After completing Star 3, go to the island. Speak to a girl named Elizabeth and she'll offer you a home valued at $300,000,000,000,000,000. Offer her $10,000. This can be used as storage or your home. This house includes a camera, three rooms, and a pool you cannot go in.