There are universal codes for bells you can find online, for one thing.
But if it's your first time playing, it's a lot more rewarding to go the long route and just earn them legitimately. Buying turnips from Joan on Sundays before noon and selling them to Tom Nook during the week can net you a large profit, but the price he offers will change daily through Saturday and won't necessarily be more than what you paid in the first place. Sometimes, but not always, there will be a large spike in what he offers one day of the week which will be double what you paid. If you don't sell them by the following Sunday, the turnips will rot and become useless. There's a thread with detailed information on all of this in the GameCube board.
Alternatively, and likely better until you make some progression, fishing and bug catching - especially the former, and especially in winter when there are few insects available - is a good way to go. Collecting a full inventory (or more) of red snappers down in the F Acres will help a lot.
Carrying furniture, carpet or wallpaper with you will sometimes prompt your villagers to try to buy an item from you, and they often, but not always, offer more than what you might receive by selling it to Tom Nook.
Clear statement is like an art object:
it is the afterlife of the process which called it into being.