- Collect the Bells from hitting all your permanent rocks with your shovel(~16000 per day, doubled if you are wearing a Lucky Item).
- Collect your four daily fossils every day, sell ones you don't need to donate.
- Collect all the Sea Shells on the beach every day.
- Shake all your trees with your net out, if a beehive falls, swing your net. You'll catch it. The Bee + hive is 3000 total.
- Collect fruit off the trees to sell.
You can also just fish and catch bugs and it'll add up. After a while, after you pay off your first home loan, you'll unlock the island where you can go in the evening (7PM to 4AM) to catch high sell price beetles. Can easily earn you 500,000 Bells a night.
Definitely getting them Tortimer Island beetles at nighttime. It’s a gamechanger.
Alternatively, you can buy in game bells with the currency on these forums, TBT, provided you have enough TBT. I once bought like 50 million in game bells.
Like Khaelis mentioned, I think the best way to make easy Bells is to catch beetles on the island once it's unlocked.
Be sure to hold the A button and/or walk slowly when approaching them.
Fossils, money rocks, bugs, fish, ore rock, etc. I suggest searching up ways to make bells in acnl, alot of people make videos of how to make a lot quick and easy. For example, catching beetles at the island at nighttime from around 10pm-12pm (or a little earlier like 9pm or so) you can make a good 300-400k depending on what beetles you catch
A big help to me is collecting the fossils every day, especially if you have the bell boom ordinance. You can get over 10k easily and that adds up over time. And then when you unlock the island, I second going after beetles and sharks.