There is a process known as market research or market analysis that is used by companies to determine the target market for a business. This is not a one way process -- you should not first create a product and then look for people who want to buy it (often a formula for failure) but instead incorporate market research into the product planning cycle.
Several techniques are used to analyze markets. You can use statistical analysis of past consumer behavior or various forms of survey or focus groups. For retail, you should look carefully at the demographic attracted to neighboring stores and make sure that your product is appropriate. Placing expensive couture in a strip mall with mainly discount stores, for example, would not be ideal.