Scinocco - That's excellent advice from Jen. I don't know enough about your circumstances to make any but the most general recommendations. If you have a car and a digital camera, you may be able to get started with shopping/auditing the major convenience store chains. There's a lot of work there and it's available on a national basis. If you're in a large city and use public transportation, the situation would be different.
I shop for a few companies that I believe have work across the nation. Those are Corporate Research, Maritz, Bare, Market Force, and Bestmark. You need to be aware that the jobs posted by Corporate Research will go up in fees until someone picks them up.
As far as building your confidence, know that every one of us started where you are now. You will have to take the first step and then the next step. I believe all of us felt nervous when we started, but that will get better as you go along. Be sure you take only one shop at first and do that one shop. When you are comfortable enough to add to the day's work, you'll know. Don't overwhelm yourself and take on more than you can handle. Build up slowly and before you know it, you'll be doing several a day.
Mary Davis Nowell. Based close to Fort Worth. Shopping Interstate 20 east and west, Interstate 35 north and south.