Hello and Welcome!
If you have not done so already, I suggest reading the "new shoppers" area on the forum. It will give you a great overview of the world of mystery shopping. Many of us are signed up with 100+ companies and most of us shop to either supplement our incomes or keep busy, for instance, during retirement. There are a small handful of folks who shop full time. A few post regularly on this board.
Me: I work full time and shop to augment my family's income. I'm in Seattle.
Hard work builds character and homework is good for your soul.