Welcome to the fourms! You will find a wealth of information here.
Yes, some MSers do this full time and make a decent living at it. However, that is not usually done by a beginner. In addition to seaching for infomation in full time shopping here, your best bet may be to star by doing a few shops while you still have your "day job." Beginners made spend a few months doing shops that pay only $5 to $19 and have to prove themselves in order to even see the postings for better paying/more complex assignments. And, you will be self-employed, running your own small business and resposible to pay quartely income and self-emploment taxes as your earnings increase.
Most shoppers sign up with about 10 companies to begin with and, if they like it, slowly expand to 100-200 companies. You may actually perform assignments for about 30 different companies in a year, but the mix will change as clients change Mystery Shopping Companies (MSCs) regularly.
The search any MSC or topic on the forums, click on "search," then select "all dates" and enter the topic that interests you.
Or, just pull up a comfortable chair and read, read, read for a few hours.
Based in MD, near DC
Shopping from the Carolinas to New York
Have video cam; will travel
Poor customer service? Don't get mad; get video.