Nestbox preparation also depends on time of year. In the cold months you want to provide more bedding, less in the hot months.
In winter I will put a couple inches of pine shavings in the bottom of the box, sometimes with shredded brown paper bags that I put through our document shredder. I then put a lot of grass hay and straw into the box, and give the doe even more outside of the box to gather up and add to it.
Straw is a good bedding material for several reasons. It is very slick, so urine will drain well from it, it is hollow so retains warm air within it, and it is stiff enough to give the nest "structural integrity" so it doesn't get mashed down.
Once the doe kindles, remove the box so you can check the kits over. Remove damp or bloody bedding and any placentas or dead kits that the doe did not eat. I like to put pelleted pine horse bedding or wood stove pellets underneath the nest "bowl" to absorb urine, making sure to cover it with the hay or straw. Some people have concerns with the pelleted pine since it becomes fine sawdust when damp, but I have never had any problems with it.
Good luck with your kits. I hope you get a nice healthy litter!
