Because about a third of my money making ideas involved collecting stuff in a number of different ways and selling it, I gave my Sim the Collector and Geek traits along with Loves The Outdoors. It seemed to pay off as I found a lot of Voodoo dolls and valuable items though activities such as digging, combing the beach for trash, excavating etc ... these were sold on a Vendor Table at a 300% mark up.
My best money makers were crafting Camping Mascots, netting me $159,708 as most of the ones my Sim made were worth about 4K each, Painting and like most people here I watched Carl's video and used the drawing tablet to earn $114,282, and Opening Chests in Selvadorada for around $73,374. Everything my Sim crafted was sold at a Vendor Table at the highest mark up, paintings were sold via that thing you can buy to sell paintings on that came with City Living. (I forget what it's called). Baking made a fair amount of money too,a round 70K, those activities were my best earners.
Buying a Holiday Decorations box and rummaging though it was surprisingly profitable, it's super quick and my Sim ended up with 285 items to sell for $53,280, I also made stealing a club activity and sold items my Sim swiped for over 30K. I came up with an idea that I'm rather proud of, the day after my Sim had made money through painting, I had her join the Freelancer career as a Freelance Artist, because she was already at level 10 painting (Thanks to reward and lot traits and club perks) she was able to take the best jobs right away, I got about 25K for that and about the same for combing the beach in Sulani.
My Sim had the Marketable and Creative Visionary rewards so everything she found or crafted and then sold was worth more money, I bought her the Entrepreneurial reward and Networked club perk before joining that career so she went up a rank while doing it.
I thought I'd be clever and have my Sim live outside for the duration of the challenge to save money on building/buying a house, that was a great idea ... until she got abducted by aliens!
Thankfully the Team let me buy a Satellite dish. I also got hit with a couple of freak thunderstorms and blizzards which surprised me as I played mostly in Summer, I didn't know that Mysterious Weather was a random Calendar thing that can occur.
I could have thought of a couple of better ideas I guess but I think most of my ideas were good.