I've only been shopping for 6 months, but I usually make 800-900 per month. There are numerous small town within a 70 mile radius. I take bonused shops in those towns when they appear, and when I know I'm going a particular place, I start looking for other jobs to do on the same day, either on the way or in that location.
My goal is $40 per day, but I regularly make more than that. I go to any length to fix anything I screwed up, and I also complete every assignment no matter how much I don't want to in the moment.
I want to be known as someone who is so frickkin reliable that they give me a job and then never give it another moments thought. Nothing will keep me from completing a shop except weather conditions so horrible that my life is in danger.
I rarely do food shops. They take an inordinate amount of time, plus they don't usually pay well. I don't like fast food and I do have to be paid to eat it. I will do most any other kind of job as long as it meets my $10 per hour, and 55 cents per mile requirement. Even if it only meets that when bundled with other jobs. Thats fine.
I take gas station routes when I can.
I agree with camelliac about the happy level.
I thrive on mystery shopping for some reason.