Know your products intimately. The more you know about your treatments, the more you will know about how different treatments can add value and convenience to the product your customer is buying, as well as how to recommend upgrades or alternatives. Customers want to buy from people who know more about products than they do. Your goal as the salesperson is to let the customer know how they could easily make the product they want better, which means you have to know that product inside and out. Do your homework to make the upsell.