Shriveling is not a good thing. Mist them lightly, store in slightly damp peat moss or shredded newspaper. Store them somewhere dark and cool, but not where they'll freeze. You don't want them too wet or they'll rot,but neither do you want them to shrivel up and dry out. Check them at least once a month throughout the winter, mist lightly as needed.

I learned a trick over at the Dahlia forum a few years back.
I had tried many ways to store Dahlia tubers with none of them working very well for me. The best way I had found was to put the barely brushed off clumps of tubers in paper bags- and those into plastic bags in the basement. Even checking them every month- I would at best have a few dry up all wrinkely- and a few turn to mush- So at best- I was left with VERY few to start anew.
I now dip my well cleaned and labeled (with a sharpie right on the tuber itself) dahlia tubers in a solution of sulpher (found in garden centers) and water and wrap them up tightly in cling wrap. Really!! I place these in to bags- or boxes- or what ever and keep them on the COLD basement floor.
I have not lost one tuber when stored this way!
I start looking at them near the end of February and into March looking for signs of growth. If there is room indoors under the lights I will start them early indoors- otherwise I will start them outdoors after the fear of frost is over.
Julie

I just did it the lazy way. I dug them up shortly after the top was frozen and blushed all the dirt off. They are stored in the basement (probably about 50-60 degrees), in a plastic bag with the top open. Over the last 20 or so years, I rarely lost any this way. Maybe it depends on the variety.