T.F.
Most of those opportnities are scams. You don't get paid for your mileage, wear/tear on your car and when you go on a mystery shop, you spend your money. Most especially don't pay the company for any materials, etc.
I've done focus groups in the past and they can be fun but still it is not a money maker.. I may be paid $100 for the hour but that does not cover my drive, wear/tear on my car/parking, my time. When I do it, I do it for fun and just go shop afterwards, not to sock away money.. there is not enough in it for that.
Maybe you can babysit, or if you are good at something like cooking, knitting, etc.... holidays are coming up so sell your crafts!