How can a person new to Wicca successfully cleanse a living dwelling with sage? What can be done to prevent a person from harming others who live within the same dwelling/home? Can these tasks be accomplished as a solitary practitioner?
You can absolutely cleanse your space, but may I suggest not using White Sage, which is sacred to First Nations people and is also somewhat endangered.
I would use three steps. First, CLEAN the space. Organize it. Remove chaos and chaotic energies. Wash down the floors with a floor wash treated with holy basil and lemongrass. wash from the center of the home towards the door. If there are carpets, mix one tsp of the powdered herbs into a box of baking soda, sprinkle on the carpet as a carpet powder, and vacuum in the same manner as the floor wash. You can also make a wood wash to clean furnishings, etc.
Once it’s CLEAN, you can use incense or a smudge bundle to cleanse the air. . I use a smudge bundle of lavender and lemongrass, but there are any number of cleansing herbs you can use. If your family is open to it, get them involved. Go through the house from top to bottom, clockwise, with pots and pans and noisemakers. Open all the windows and make a lot of joyful noise while wafting the incense throughout the space. Light a small candle (tea lights are great) in each room. Visualize all negativity exiting through the windows and doors. Have fun with it.
NOW, do your protection work. Lots of ways to go about this. I bury a clove of garlic in each corner of my yard, along with an iron nail and some of my own urine, YMMV. If you don’t have a yard, placing a stone at each quarter in the house and one in the center of the house to create an X is another way to create a protective ward. If you are concerned about unseen energies, sprinkle salt at entrances. This protects the dwelling and the people in it while they are home. Personal protection outside the home is a separate topic.