I went with the connections & jobs, 2 painting clubs plus photography route, boring but it does give a lot of money. My sims were married to speed up completing SoulMates for the points for connections. The painting clubs were easier to track because the husband had all lads, and the (alien) wife had all lasses. I started to run out of real time and had to drop photography after the 1st Wednesday otherwise I would have made more money.
I went with the most expensive houses I could afford, but plowed as much of the upgrading as I could into floors and wall papers to avoid some of the depreciation.
My sims also complete Painter, Wealthy and Mansion aspirations along the way so plenty of points for moodlet solvers, plus the bonus from shrewd and the rebate from build mode both helped.
Lastly, I want to say a thank you to
@oshizu for her super useful posts on Towns & Townies which made planning this one so much easier.