To begin with the sell everything approach ( see here) isn’t that bad. It can help you define your researching skills whilst also developing your selling skills and making you a profit. However if you really want to make easy money on ebay then you will eventually gain a great deal from moving on to the focused method.
This method of selling on ebay is where all the top sellers make their money. They focus on one particular type of product and then focus solely on these types of product. Some will even go a step further and specialize in one area of a certain product. A quick example of this is instead of someone selling video games they will sell video games for only one console like the xbox 360.