The MSPA can be a good start, but they only list member companies there. This represents only about 150 or so companies out of the 400-500 companies out there that DO mystery shopping. Also try volition.com, walletboosters.com, mymommybiz.com, or search for "free mystery shopping companies"...but all of the sites listed above already have a list of companies with links (just click on the companies name). I know that it sounds like an ominous task to register with even 200 companies, but if you only register with 5 companies a day, by the end of your first month, you'll be FAR ahead of most new shoppers. You'll likely find that your work will come from 5-10 companies, but you never what company shops for what business in your area. If a company has no shops in your area, you're just out a little time spent registering. But, if an when they DO, you'll be there to apply for the assignment.
Another place to register is shadowshopper.com (they ALSO have a list of MS companies),but DO NOT PAY ANYTHING. Sign up for their free bronze level membership ONLY! This will give you access to their all of their "Shopper University" training information (very much worth taking some time to study for a new shopper) and free certification in shopping and merchandising if you are interested. The MSPA Silver course is worth the investment if you are "serious" about being a shopper, but it is $15, so I wouldn't take the certification test until AFTER I have studied the ShadowShopper training stuff and was "comfortable" with what is required to be a "good" shopper. ShadowShopper will try to get you to "upgrade" and pay for reduced "trial" memberships, but they have a policy of "automatic renewal" at regular rates with "NO REFUNDS" under any circumstances. I suggest that you DON'T DO IT! Most of the free emails they'll send you telling you about "opportunities" in your area are for jobs not really in "your area", but in "your STATE" and are not worth taking. But, occassionaly, they'll send you an email where the company that is looking for shoppers lists their name in the part of the email that you can see. If you are not already registered with that company, do an internet search for them and register for free.
I also suggest you register with jobslinger.com. You can search for jobs posted by four or five companies all in one place there.
I have "rattled on", and, while I have more suggestions to help you get started in MSing, this should help get you going.
I will add that you should keep an alphabetical list of the companies that you register with together with your shopper # and any "unique" log-in information for future referrence as you'll never remember it all for so many companies.
nwazshopper
MSPA Silver Certified
Shopping NW Arizona