I'm glad that you advised people to seek professional help if they're not really sure how to proceed about cleaning upholstery.
I work for a professional upholstery steam cleaner company, and you would be amazed at the damage that people do to their upholstery -- albeit with the best of intentions -- before they bring it to us and then expect some magical fix.
And while sometimes we can do miracles to get certain kinds of stains out, a lot of times the fabric is just too damaged by all the things that the customers have put on it to try and get the stain out before.
So, I would just like to repeat, people, see an upholstery cleaner if you're not sure. You can very well end up doing permanent damage to your fabrics if you don't use the right cleaner in the right amount, and even then it's risky.
We're here to help, but there's only so much we can do, so if you are at all in doubt about cleaning your upholstery, seek professional help.