Cross selling is possibly the most effective method of marketing in existence. It involves selling related or complementary products and/or services to an existing customer or client. Cross-selling is most common in the financial services industry which includes mortgage financing, real estate investments, tax return preparation services, insurance brokerage services, and accounting.

A statistic that is often cited: Companies are 60% to 70% more likely to sell to an existing customer, whereas the likelihood of selling to a new customer is 5% to 20%.

Upselling is defined as add-on or suggestive selling. This generally takes place when additional products or services are offered or suggested to the buyer of the primary product. Common examples include upgrades, a warranty, an extended warranty, or insurance. Upselling is very common in the automobile sales industry and new home sales industry.