Store at approximately 55 to 59 degrees, in a basket, box or shelf lined with newspaper. If you notice your sweet potatoes starting to shrivel, it is time to cook them. The simplest is to roast and mash the sweet potatoes and freeze in quantities you will use in recipes such as a quart freezer bag or in 2-3 cup measures on a baking sheet, then add to a freezer bag. Take out what you need.
If you are interested in blanching and freezing this website has some good information: