Gardeners have different ways of doing this and each method can work.
While some wait until the plant foliage has withered from frost, that's not absolutely necessary. My tender bulbs are planted in pots. I dumped the contents out the other weekend and shook as much soil as possible from the tubers then laid them on a tarp in the sun. At the end of the day I put them in paper bags and placed them in the basement about 15 feet from the furnace.
Some gardeners store their tubers one layer deep in cardboard boxes. Slightly moistened peat moss is used to cover them.
I know one gardener who stores his in an unheated garage until about mid-November, when the weather becomes consistently cold, then he carries the boxes to his basement and stores them there at just below 15 degrees Celsius.
Another gardener washes the dirt off his clumps and separates them into single tubers. He then dries them thoroughly and puts them in a plastic bag with very dry vermiculite. He removes as much air out of the bag as possible as that causes them to deteriorate.
He stores them in a cold room and emphasizes the need for a cool environment or they will disintegrate.
A simple procedure used by yet another gardener is to dig up the tubers and store them in grocery bags in a dry, cool basement.
If you are trying to dry your tubers, it’s okay to leave them outside in the sun for a few days. Just bring them in at night as the dampness will counteract the drying process. Check the temperature for any frost warnings, as you’d want to bring them in to avoid those as well.
Check your tubers periodically to make sure none are rotting and that no pests have gotten into them.
Around mid-March you may notice the beginnings of green growth on your bulbs and tubers.
You can pot them up at that time and start placing them outside in early May as long as you cover them during nights when low temperatures are forecast.