@aaronrulz I have a house that has perfect garden. I place the lot down in one of the worlds and have my Sims visit the people that live there and harvest from their garden. I then start my own garden using their 'perfect' harvestables. My brother teases me that this is cheating, but gardening takes forever to get to 'perfect'. Now that I have one house that has perfect harvestables, I never start gardening from scratch. Gardening is the fastest 'get rich quick' method that I know. I also have a Club called Pixel Perfect & I have the club members gather at my Sims house. All the paintings they create you collect the profits. I have a room with 12 easels, as the only approved activities are paint & friendly socials. As the Sims finish one painting, I collect the profits and they move to the next easel. I just do that for a few hours and I make quite a bit of money off these people painting.
I also have a retail store. I've been working on that for months now. I finally have all the perks and it's a money maker. So I transfer money to my household from the store as well.
I also like writing as you collect royalties daily. I try to stay away from music activities as the royalties aren't as large.