A clean couch makes a bigger difference than you'd think. Here's the most effective method, plus the mistakes most people make.
Use the upholstery attachment to vacuum all surfaces, crevices, and under cushions. This removes crumbs, dust, hair, and allergens.
W = water safe, S = solvent only, WS = either, X = vacuum only. This determines which cleaning method to use.
For W-coded fabric, spray Vibes Multi-Surface Cleaner on stains and blot with a white cloth. For S-coded, use rubbing alcohol instead.
Sprinkle baking soda over the entire couch and let it sit for 20 minutes. Vacuum it up -- it absorbs odors and oils.
Use a soft brush to restore the fabric nap on textured upholstery. Fluff cushions and rotate them for even wear.