In both PC and Console versions of The Sims 3, there is a really easy way to get money without a career track and without cheating.
Purchase a computer and start writing fiction novels to gain quick writing skill points. You won’t make much money from these right off the bat, but keep increasing your skill so you can write more types of genres.
Once your skill gets fairly high, start writing Romance novels to receive the most money. Soon you’ll be writing best sellers, and you’ll be making more simoleons every week than you can from most jobs, or even from owning all of the local businesses, and it takes a lot less time as well.