It's best to use water when cleaning roots.
In January 2000 somebody asked on the herblist how people were cleaning roots ... she'd been told long ago not to use water.
On small roots, like valerian, I use my fingers and lots of water.
On larger roots, like dandelion, burdock, or yellow dock, I use a root veggie brush and lots of water.
Using water is the single best way to get rid of all of the mud, clay, and small stones. And the earthworms.
Sometimes people will try to scrub the skin off the roots, too. That's not necessary. If some skin is gone off the roots after you've removed the dirt that's OK, but don't even try to get rid of it all - usually there's lots of goodies in and under the skin.
Slice things up and let drip dry before making your tincture. Or use a towel.
Or slice things up and leave on an old bedsheet on a layer of old newspapers to dry, if you're drying roots for storage.
Using water to clean leaves now, that shouldn't be necessary. Sometimes it is, though, and if you're after the basal leaves of biennial herbs (like mullein) or perennials (like dandelion) you might need to wash them, as mud spatters on low and wide leaves when it's raining a lot. Pat your washed leaves dry between sheets or towels before tincturing or drying, especially if these leaves are fuzzy.