New Horizons provides several effective ways to produce many bells in a short time. These are some of the most effective methods we have found.
Five rocks are scattered on each island. Hitting most of them with a spade or ax will produce a stone or iron block, but one of the rocks will produce ACNH Items when hit.
When you first leave the island, you will notice that fruit is growing. It is randomly selected from five options: cherry, apple, peach, pear, and orange. This is your "local" fruit, which sells for 100 bells per piece. Not terrible but not very good.
Now, if you manage to get one of the four non-native fruits and bring them back to your island, these fruits are priced at 500 bells.
When buy Nook tickets, you may find non-native fruit trees on various Nook islands discovered earlier. Bring the fruit back to your island and harvest it in a few days. You can also choose to Buy ACNH Items from ACBellsBuy.com to save a lot of time.
If you have friends playing, this process will become easier. Not only can you collect your friends’ native fruits and sell them in town, but you can also bring them and sell them for 500 bells in their town.