A damp cloth, wet with hot from the tap water, will work to clean any juice residue from the threads of batteries and atomizers. And clean the outside of those things. You can just blow out the atomizer when changing flavors. Once a week you can let the atomizer soak for awhile in the hot tap water and then dry at least overnight perhaps 24 hours if you feel strongly about wanting things to be clean.
I only clean my atomizers when they become hard to draw or when I'm changing from a very strong flavor. Warning, nothing including dry burning, seems to completely remove the taste of menthol.