Start off here reading through the "New Mystery Shopper" section. It gives you some basic how to information both for getting shops and organizing your business. There are plenty of legitimate companies out there and you will be asked for your ssn and other data to work for/with them. Just make sure that the company websites you provide that information to are companies you have found from legitimate lists of companies, such as the one here in the first post of the first thread of the "Mystery Shopping Company Discussion" section of the forum, from the list at Volition.com or from the list at the MSPA website. And watch the URL bar at the top of your screen to make sure that the site you are providing information to starts out "https://" so that you know your information is going to a secure website.