Summarize the following:
Use a soft bristled upholstery brush or baby's hairbrush and go over the entire sofa in small circular motions to loosen up any impacted dirt. Go over especially soiled areas in a back and forth motion until the area is clean. The soft bristles on your brush should not damage the fabric. Set the vacuum to the lowest setting and attach the upholstery brush to it. Use the attachment to lightly go over the surface of your couch and suck up the dirt that you loosened with brushing. Vacuuming regularly prevents dirt from becoming embedded into your sofa's fibers. You can brush your sofa more often, or whenever you notice that there's been a buildup of dirt and dust. The more often that you vacuum and brush your sofa, the less often you'll have to get it professionally cleaned.
Brush the surface of the sofa. Vacuum the sofa with the upholstery attachment. Continue to brush and vacuum your sofa on a weekly basis.