Before cleaning your upholstery with any solution, always read the instructions on the label of your furniture to prevent damaging your furniture in any way.
Before you start, always test a small hidden area first.
1. Mix a quarter cup of a liquid dish washing detergent with one cup of warm water, and whip up until it is foamy. Other products to have on hand are white vinegar, ammonia, hydrogen peroxide, isopropyl rubbing alcohol or hairspray, and a professional dry-cleaning solvent.
2. Test first on a tiny area; use just the foam and a clean white cloth to scrub gently.
3. Clean a small part while you work at a time, and overlap as you work to avoid spotting.
4. Dry it off using a fan to ensure thoroughness.
Do not use laundry detergent
The residue left behind might attract more dirt over time and leave your upholstered piece dirtier than when you started. Always use clean, white towels or diapers.
http://londoncleanltd.co.uk/carpet-cleaning.html state that to prevent accidental damage during this process, keep the upholstery as dry as possible throughout.