After buying Popper Ice Cream Property, you can start selling ice cream. 
The challenging thing is, every 4 ice cream sold you'll get one wanted star, so try this; 
drive a popper van to Pier area. Park the van on side way facing to the pier and press 
capslock to activate the music. People will start to buy the "ice Cream", and once a wanted 
star appear, hurry drive the van to gate pier 1 and turn back to the sideway. 
The one wanted star will disappear on the way. Repeat this every selling around 4 ice cream. 
I made 100 sales and completed the Popper Ice Cream Property, which generates money up to 
around $3000.