Generally my answer is "I don't". If I have a dog (pup) that still has an occasional accident in the crate I will put shavings in there, just in case. Or if we are going somewhere that I expect the dogs to get wet (swimming, herding, it's raining out, whatever) then I'll put shavings in there to help dry them off once they are back in their crate. Otherwise I generally don't put anything in crates. I've had dogs that were great with bedding for a long time, then one day decided to chew it up. Only needed to come home once to a dog who had chewed a hole in it, put their leg through it, then turned in circles making a nice tourniquet on their leg. Luckily it wasn't like that to long, the foot was VERY swollen but once circulation was restored no permanent damage was done.
If I do put any sort of bedding in, it's something they can't chew dangerous holes in. Hay, shavings, newspaper, fabric (old towels or blankets) cut up into approx 4 inch squares, etc.