you wish to keep them as houseplants, then you do not have to invest much time and effort for its care. It has to be planted in a mixture of soil and sand and not just in sand. It should be kept in a location where it gets enough sunlight exposure. Water it regularly, but over watering should be strictly avoided.
Read more at Buzzle: http://www.buzzle.com/articles/cactus-plant-facts.html