As far as something simple and effective, I don’t think it gets much simpler than smudging, also known as saging or smoking, a space to rid it of negative energies. It has been my experience that this is the most well known and most widely used way of smudging.
Smudging, or the sacred smoke bowl blessing, is a powerful cleansing technique started by The Native North Americans which actually dates back millennia. Most traditional cultures, including the Zulu, and Chinese, for example, have age old rituals for blessing and cleansing. It is impossible to say for certain when smudging actually began, but early civilation came to know that the smoke from particular herbs had beneficial effects for humanity. Originally mixtures of sacred herbs, as well as resins, were burned in a special bowl and the smoke was then wafted around the person or place that needed purification and cleansing. Eventually it was found to be simpler to bind dried herbs together either with colored string, or a strip of hide to provide an easier way of smudging. In addition to cleansing and purifying, the Native North Americans see smudging as a way of shifting between various levels of reality, connecting us here in the material, physical world to the subtle spirit realm.
Originally sage and sweetgrass were the predominant choice for smudge. Sage drives out any negative thoughts, influences, energies or spirits, while sweetgrass is used to attract positive energy. Although these two ingredients alone are quite effective, the blend has a myriad of particular mixtures, for specific uses, here are just a few:
Cleansing mix for a new house: Sage, sweetgrass and juniper
Emotional cleansing (after arguments and in relationship rituals): Sage, cedar, lavender, and borage which is optional.
Mental clearing mix for clarity: Rosemary, juniper, pure tobacco, sweetgrass.
Healing of mind and body: sage, cedar, lavender, and echinacea which is optional.
Spiritual mix, for divination, intuition and calling on the spirits: sage, mugwort, copal or frankincense resin, lavender
The recipes are limited only by your imagination. When making mixtures for particular uses and ritual the general concensus is that it is far easier and convenient to mix dried herbs in whatever desired ratio that is most pleasing to you. It is best to use a charcoal block and then add the mixture a pinch at a time to keep a strong and continuous smoke going, rather than putting in a large amount which omly burns what is in direct contact with the charcoal and you then have to stop and try to scoop it up to re-add it. One thing that is definetly worth mentioning is that you can use culinary sage if need be. You can then use your mixture in whatever ritual you have chosen for the issue at hand.
There are several good, reasonably inexpensive books available regarding smudging. My personal favorite is: The Smudgings and Blessings Book by Jane Alexander. The reason I favor this book is it is extremely informative about the Native American beliefs, it gets into how they view the quarters and what each direction represents to them. In addition to a super enlightening section on that, she then moves on to the Wheel of the Year and our Sabbats, so their is a great deal one can learn on multiple subjects that would be of interest to anyone interested in both the Wiccan religion, as well as getting some education on another pagan belief system.
The other book I have personal knowledge of is : Sacred Smoke by Harvest McCampbell, this book was given a very high rating by a good friend, but I myself have not read it.
There is also a web site: Weloveincense.com, which gets into smudging as well.
My first personal contact with smudging was about 25 years ago in a strictly Native American setting, but I integrated it into my personal life very quickly with always positive results. One other thing worth mentioning is that in my researching smudging I have seen it said in the Wiccan context that after a person smudges to remove negativity, you should then burn incense of your choice due to the belief that removing the negativity from a space leaves a vacuum. I have never subscribed to this philosophy due to the fact that I always use sweetgrass in whatever blend I make because it attracts positive energy to the space, but I felt this was definitely worth mentioning in my attempt to share information and educate. Brightest Blessings!