Cash Strategies

The secret is house farming and getting your multiplier up.

If you are still working through the regular levels, just be patient. Buying all the level buildings will keep you poor for a while, but once you get past that you'll eventually have plenty of cash to spend on things.

It depends how far you are in the game. You could consider buying a few more houses to boost income:
https://forums.ea.com/en/the-simpsons-tapped-out/discussion/101056/house-prices#latest
Have all Springfield Heights main buildings in your town for the hidden bonus, increase your multiplier, buy all 5 beach hideaways and upgrade them....
https://forums.ea.com/en/the-simpsons-tapped-out/discussion/90074/tips-for-new-players/p1
https://forums.ea.com/en/the-simpsons-tapped-out/discussion/81718/sh-tables/p1

Keep using the shortest tasks you can, but make sure you can collect on time. If you use a 1hr task, but it takes you 5 hrs to collect, youre losing money. I used to use 1hr as much as possible, 4hr while at work, and 8 or 10 hr tasks overnight

Cash: House farm. Blue and purple houses. Save money to buy a square of land, fill it with houses, repeat. Send characters on tasks over and over. Use XP collider as often as possible to collect donuts to buy decorations that increase your xp multiplier. XP increases the amount of cash and donuts you receive for house farming and donut farming.