Upsell

Encouraging a customer to purchase a higher-value version of the product they're already buying, or to add premium features.

Selling to someone who is already in a buying mindset is far easier and cheaper than acquiring a new customer. Upsells directly boost AOV.

A customer adds a £20 face serum to their cart. At checkout, you show them the same serum in a larger size for £30, saving them £5 per ml. Many choose the larger size.