To keep potatoes from going bad you should store the potatoes in a cool dry and dark place.
If you have a cellar or basement you could put the potatoes in there.
You can also cover the potatoes with some dirt to help keep them from going bad and then wash the dirt off the potatoes when you're ready to use them.
Or at least store the potatoes in a cool dark pantry to keep the potatoes from going bad.
Another way to preserve potatoes is to cut them up, blanch the potatoes and then put them in the freezer.
Then you can make fries and other fried potatoes that way.
But it's best to use potatoes for other things before they have a chance to go bad.
it's never a good idea to buy more potatoes than you need because they do go bad quickly.
But storing the potatoes in a cool dark place can help preserve the potatoes.