The easiest way to make money in the Sims Online is now to make your own custom content and sell it. To do this you will need to purchase a store lot, which of course takes money. You can exchange real-world money for Simoleons if you wish, or you can work in-game to make the money to buy a store. The economy and employment features of EA Land are changing day by day now that custom content is available, so keep checking in for the latest developments.
In the Sims online you can choose between working in one of the four official jobs or you can team up with other players to start your own business enterprise. Although it is technically possible to work as an individual, it is much harder.
The official jobs are:
The team jobs you can do for yourself mirror these, and are:
Personally, I'd opt for the team jobs where you work for yourselves as they are more fun and earn you more money. Then when you've got enough Simoleons together for a store it's time to think about owning your own business. Remember that those Simoleons will soon be exchangeable for real-world currency, so get cracking!