When doing the Cherry Popper drug deals, it is easier to just go to the beaches and sell. Once one star is achieved, simply drive around until it disappears. The bonus to doing it this way is that you will always have plenty of customers, and no cop cars. The only downside is that the ice-cream truck moves very slow. However, you can easily outrun any on foot cops. Try this to make 100 sales easily.

When playing the mission, you will notice that the "Ice cream" is most popular among prostitutes.