FRUIT

Foreign fruits are the absolute, best way to make money. An orchard is
basically a town filled with fruit trees and few to none normal trees. As you
must know, the fruits that you start with(native fruit) sells for only 100
Bells. Foreign fruit sells for a whopping 500 Bells apiece. To plant fruit
trees, you must bury the fruit with the shovel.

There's always the problem of getting foreign fruit though. What to do? For
those with wifi, you can run into someone else's town and take some fruits
from them, with permission of course. If you don't have it, you're not out
of luck. Just pack some native fruit into letters and send them(along with a
short message) to the villagers of your town. If you're lucky, they'll send
you some foreign fruit in return. You can also find coconuts along the beach.
Make sure that if you're going to plant them, plant them near or on the
beach.

Once you get your fruits, chop down all the trees you don't want(I left my
pine trees alone, just so when I shake them I get a guarantees 100 Bell/bees/
items) and plant your fruits. Make sure you keep the trees 1 or more spaces
apart, not right next to each other. Not only will this make it easier for
you to pick fruit, it will give you a higher town rating. Wait a few days for
the trees to grow. If your trees aren't growing, plant them in different
spots. For some reason, some spots just won't allow trees to grow.

After you have your orchard blooming, just harvest the fruits and sell them.
You'll gain 7500 Bells for each trip(assuming you have empty pockets) and
can make over 100,000 Bells in a day. The only setback to this is that you'll
need a lot of time to shake all those trees and carry the fruit back. I
personally use this method, though I don't usually clear my entire town in
one day.