Recently, I was asked for this info so I thought I'd post it.
Sage has been used for ages by indigenous peoples to cleanse and raise the frequency of vibration in a place or person. Also, visualizing a bubble of Divine White Light surrounding, filling, and protecting a space (or you) cleanses and protects it. Long instructions follow, but it's a simple process...
Spirits dwell on the Earth plane for only a few reasons: they want to communicate a message, they are watching over & protecting a person, they can't let go of their earthly life and want to continue it through a living person, or they want to avenge a perceived wrong. You can easily rid a place of a negative spirit by invoking the Divine and directing the spirit to the Light. You can raise the frequency of vibration in a space so that it is incompatible with the energy of the spirit and so the spirit leaves.
First, create a sacred space by invoking whatever aspect of the Divine has meaning for you: the Goddess, Holy Spirit, Christ, Angels, Archangels, The Great Spirit, Buddha, All That Is, Higher Power, Spirit Guides, etc. Affirm that only the highest and best of the Divine is present. Affirm that you know only Good can be in this place and only Good can come to you. Add whatever else you like. Ask the Divine to bless the smudge stick and give thanks.
Holding the smudge stick over something to catch ashes (I like to use a big seashell), light the fat end until it flames. Blow it out so a stream of smoke rises from it. Relight and blow out as often as needed to keep the smoke going.
First smudge yourself by moving the smoking stick around the outline of your body. Lift each foot, smudging under it too. Then, walk the perimeter of the room gently waving the stick back and forth to spread the smoke--not thickly, just a light "dosing." As you do this, ask the element(s) of the Divine you have invoked to bless and protect the space. If you like to sing or chant, this will greatly add to raising the frequency and consecrating the space for Good.
If you feel a specific spirit with negative intention is present, emphatically tell him or her aloud that he or she is not welcome in this place. Tell the spirit he will find the true peace & love he seeks by going to the Light, even if he may not believe it. Tell him to look around and "see" the Divine (the Angels, Jesus, Buddha, Goddess, etc.), welcoming him. Tell him to "find" the Divine Light (imagine the Light at the end of a tunnel that appears when we make our transition) and move into it. Direct him emphatically to go to the Light. Repeat it all several times--not welcome, go to Light, will find what he seeks in the Light. Affirm that only the Divine--Light and Good--can be present.
Move from room to room repeating the procedure, then return to where you started. Conclude with thanking the Divine for its presence, love, and aid. Extinguish the smudge stick by pressing it into the shell until all glowing embers are out.
You will feel when the negative energy has left. You may need to repeat the smudging several days in a row or once a week for awhile.
I also like to ask the Divine to bless some small white stones/pebbles at the same time I ask for the smudge stick to be blessed. The stones "anchor" the Divine energy in the place. I place them unobtrusively in the four corners of the room or the building before I conclude the ritual.
