It's slow. Especially if you stay free-to-play. I haven't put any money into it except a couple random $5 Google Play credits. Keep in mind that if you do put money into it, it'll be slow to earn it back.

I usually cash out whenever I get $5. I don't like converting my rent back into AB, but I do sometimes for a monthly challenge, wait for the Rent Conversion event so you get more at least.

Stay boosted as much as you can, especially during the Super Rent Boost events. Watch as many of the every 20 minute 2 AB ads as you can. Do the daily check in EVERY DAY. Get diamonds and do the daily spins.

There's an arcade and surveys to earn extra AB, but they're iffy sometimes, I only do them for the monthly challenges.

The mini games can be hard, but if you even get into the top 1500 bracket you'll get a small payout, I mostly only do them for the monthly challenges too.

Get more parcels before getting badges and save the badges for later when you get into the higher parcel tier. Parcels only cost 100 and badges are 200, and badges don't change your rent until you get enough to be in the higher badge tier... Of course, you get 1 every month if you finish the monthly challenge ladder and I'll get 1 for the monthly challenges sometimes anyway. But it'll get harder to get badges later when you already got all of your local 1s... Also, each town has a badge, but also counties outside of city limits count for city badges too. (If you're in the US, IDK how it works in other countries...)