The best place to start is with companies that have shops in your area. Those can be found by signing up with Jobslinger.com Put in your zip code and how far you are willing to travel and see what companies have posted jobs. These companies are the ones with clients in your area and although the jobs you see on Jobslinger.com have probably been taken and performed already, it is an excellent resource to find what companies to sign up with.
Otherwise, Corporate Research International has jobs pretty much all over the country. Their pay is low but it is an excellent place to "get your feet wet". Shop 'N Check (now called Market Force) is another company with generally low paying jobs around the country that are good for a start. You will eventually want to sign up with many many companies but these are good because if you totally mess up you won't have shot yourself in the foot if they deactivate you. What you want to avoid is starting with a high reimbursement job, messing up and not getting reimbursed. You also want to avoid starting with companies that have higher paying jobs because you don't want to mess up your chances of future jobs with them because your first jobs were a disaster. Trust me, we all have disaster shops at first.