Vacuum your sofa thoroughly. Wipe down any hardware or wooden or metal armrests and feet.
Shop for slipcovers or interior acrylic paint, depending on how you'd like to redo your sofa.
Collect paint or fabric swatches for your sofa. Choose a solid color, with one or two patterns for cushions or accent pillows, or go with one or more solid colors or patterns, depending on your taste. Compare different color and pattern combinations.
Measure your sofa. Write down the dimensions, and take them with you when making a final decision for a slipcover. Purchase a slipcover closely matching your sofa's body style and size. Purchase 1 gallon of acrylic paint if you're going to paint the sofa instead.
Wash, dry and iron the slipcover. Dress your sofa with it per manufacturer instructions. Zip, tie or fasten it completely. Look at the slipcover, and note where you'd like to make changes. You may want to cut out the center, for instance, and sew new cushion covers in a contrasting color or pattern. Pin and mark any areas you'd like to alter to fit the sofa better, for instance, the armrests or bottom corners.
Make your alterations using a sewing machine. Measure your sofa cushions, and sew covers using your desired fabric. Use the current sofa cushions as patterns if need be. Install a zipper or Velcro on one side, and place the covers on the cushions.
Sew new covers for small accent pillows, or purchase ones that match the new slipcover and cushions. Place them on the couch.
Remove any sofa pillows, cushions and hardware. Place a drop cloth underneath and around the sofa.Tape down all wood, metal or framing and feet using painter's tape.
Mix 1 part paint with 2 parts textile medium. The medium helps keep the acrylic flexible for fabric use so it won't crack.
Apply the mixture using a paint roller for large areas. Apply finishing touches with a small brush. Allow the sofa to dry completely.
Remove the painter's tape. Reinstall any hardware you removed before. Place freshly covered sofa pillows on top.