In Shamanic tradition and now commonly used amongst energy workers, white sage is used for cleansing your home environment, your aura as well as Crystal's or anything you want to cleanse of negative energies. To use the sage you would need to burn it as you would a stock of incense. To keep the smoke flowing you might need to gently blow on the embers.
yerba santa herb is used for protection, setting boundaries, clearing space of negative energies including the energy from illness.