A clean fabric couch makes a bigger difference than you'd think. Here's the most effective method, plus the mistakes most people make.
Look at the tag for cleaning code: W (water), S (solvent), WS (either), X (vacuum only). Use the appropriate method.
Vacuum the entire couch including under cushions and along seams. Remove all debris before wet cleaning.
Apply fabric stain remover or a few drops of dish soap directly to visible stains. Let sit 15 minutes.
Mix Multi-Surface Cleaner with water. Dip a soft brush and scrub the fabric in circular motions. Don't oversaturate.
Blot up moisture and loosened dirt with a clean microfiber cloth. Air dry completely before using.