A clean fabric couch makes a bigger difference than you'd think. Here's the most effective method, plus the mistakes most people make.
Lift up a cushion and look for the manufacturer tag. The cleaning code is one or two letters: W (water-based cleaners only), S (solvent-only — no water), WS (either is safe), X (vacuum only — professional clean for everything else). Skip this step and you can ruin a couch in one wash.
Vacuum the entire couch with the upholstery attachment. Lift each cushion and vacuum the deck and the back of the cushion. Use a crevice tool along the seams, around the welt cord, and where the cushions meet the frame. Pet hair and crumbs need to come out before any wet cleaning, or scrubbing turns them into a stuck-on mess.
Apply a fabric stain remover or a few drops of dish soap directly to visible stains. Work it in gently with a fingertip and let sit for 15 minutes. For old set-in stains, repeat the application — fresh chemistry beats one long soak.
Mix Multi-Surface Cleaner with warm water in a spray bottle or bucket. Dip a soft brush or microfiber-wrapped sponge and scrub the fabric in small circular motions, working in 1-square-foot sections. Do NOT oversaturate -- if water is pooling on the surface, you have used too much.
Blot up moisture and loosened dirt with a clean dry microfiber cloth. Press, do not rub. Move to a fresh section of the cloth as it picks up grime. Repeat the section if water comes up dirty.
Let the couch air dry completely before sitting on it -- usually 4-8 hours with a fan running, longer in humid weather. Once fully dry, apply a fabric protector spray (test a hidden patch first) to repel future spills. Reapply every 6-12 months.