i put down a layer of chipped/shaved Aspen and then put some shredded aspen on top. i place moss in here and there. the snakes will do their own mixing as they scoot about the enclosure.
this combo works well for me and my snakes. i got some that like to burrow so it adds a little to their comfort i hope. i don't have a huge collection and mist almost daily. it holds moisture and gives me a chance to peep my snakes.
alot of folks prefer cypress mulch for holding better moisture but i don't like the size of their individual chunks of wood. the same can be said for Eco-Earth on holding moisture but i find the pieces to be too small. and then some folks use paper (paper towels, newspaper, etc.) for it's ease of cleaning.
anyway that's what i use, do and think. your mileage may vary.
-- Ax