Generally, if you feed a high quality food, make sure the kitten is free of any and all parasites and clean the litter box often, and it shouldn't smell.

Yesterday's News is nice and relatively inexpensive, there are also some smaller paper pellets, looks like clay but isn't.. Hm.. Tidy Cats(multiple cats type) works really well, and they have the crystal type too. I try to stay away from anything that is made of clay as it just fills up the landfills and doesn't go anywhere. They have a flushable kind now too.

And then there's the litter box with self-washing, reusable litter, that dumps right into the toilet. *love*