Tutoring firms can benefit in a predictable and measurable way by cross-selling products to current clients.  One of the nice things about cross-selling is that it implies an high level of engagement between tutor and client.  Most folks reading this now have probably engaged in add-ons (or cross selling)  just to provide excellent client service without actually understanding the inherent benefit to their business.  As the Test Prep & Tutoring world becomes more commoditized  th