@Kyrat4216 Not saying anything about your writing skills, which seem to be fine, but one thing that will help immensely over time is learning how to write detailed and concise narratives. Many community colleges offer business writing classes. Even creative writing helps. The better you are at painting a picture of your shop experience, the more likely you are to be recognized by editors and MSC owners when they need shoppers for high-end, high paying shops. It can take years before those offers come in, if they ever do. However, the better your reports are, the better your chances of getting them.
Another thing to look into are Mystery Shop conferences. There are a few held throughout the year. Great places to get training and knowledge. Yet, the best thing you will get from them is exposure. Putting names to faces can help tremendously over the long run. Assuming that you also build a reputation for reliability. Otherwise, names to faces doesn't help so much
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Given that you don't need to make that much (and yes, $50 a day average should be easy), you've got flexibility to do a wide variety of shops. That helps you get more exposure and experience. Keep a record of the types of shops you do, i.e. apartment, retail, automotive, banking as well as the numbers you have completed. Make a file where you keep all the kudos you receive from editors and schedulers. Crate and maintain a Mystery Shop resume. You won't need it very often, but as it grows, it can be helpful to have a summary of your industry experience.