You need note down how the customers are welcomed and treated. Are their (its you here) queries being answered properly? Are the customers satisfied with the price and quality of products and services ?
Although mystery shopping is a good idea to make money, it doesn’t really make you rich. You can make anywhere between $15 to $35. Some companies doesn’t pay money rather they give small gifts or a meal voucher. You are supposed to apply for many companies and a company which selects you might give you only 3 or 4 clients per month.
One more option for you is to make money from Paid Surveys. An advantage with this is you can do the work from home if you have computer with Internet connection. Though there are hundreds of Paid Survey companies on Internet promising great money consistently, paid surveys are far away from that. It really needs a lot of hard work and sometimes smart work. You should be really careful about the company type, its history and the reality in payments to be received.