Well, I just let them live in my jar of kefir and strained out a bigger and bigger raft of grains last year. Then once the wood stove was going at the air was dry in the house, I put them on a paper towel in a basket on a bookshelf and checked them every day, stirring occasionally, until dry. Then I put them in a small glass jar in the freeze with a slip of paper with the date on it. From this jar, I take grains to send/give to people and also to start my kefir up after a loss of my own grains and a brief break from it when I was totally overwhelmed by life.
I think it is important to have that little safety net of a few dried grains in reserve, and a network of people that can return some to me if I completely kill/lose mine!
I just pull some of the grains apart into smaller pieces (quicker drying), put them on a piece of wax paper, and put that in the dehydrator at the lowest setting. The lower the heat the less likely you'll cook the good beasties. My machine's temperature control goes down to 105*F. I have mine in a jar in the 'fridge, and I try to remember to replace them with newly dried bits every 6 months or so. Like free I think it is important to have a backup supply, though so far I haven't had to resort to it.
I have been afraid to put mine in the dehydrator...I never thought about letting them naturally air dry...DOH!
I put my extras into a jar of filtered water in the frig. I change out the water a few days after adding more grains since they dirty up the water a bit.