You should buy as many of the functional items as you can. Espescially the Air Hockey Table. It can get you a lot of coins, I promise.
Instead of doing long jobs, do the small jobs instead. You can fit in many small jobs in the same span of time as a long job, and you will net more money and experience.
Great Car When You First Start:
When you first start your game, go to Bye Cars and then click on the Mystery Box and you can net a fantastic car.