What to do with those self stick curlers that just lay around in the bathroom in all different colors? They make great cactus plant holders! Fill them with dirt, and water little. They keep the cactus dried out enough to grow, and make a beautiful cluster, stuck together!
Certain cactus can be propagated by removing and planting the pups produced by the main cactus. Others require special handling to propagate from cuttings. These may need to be grafted to another cactus. Do some research before attempting to grow cactus from pups, for best results.
This is a page about helping a dying cactus. Determining why your cactus is not thriving can take some research.