WooCommerce can suggest other products to increase the size of each order.
Two techniques
- Cross-selling: offering complementary products in the cart — a case to go with a phone, for instance.
- Upselling: suggesting a higher-end version on the product page itself.
You set these suggestions up in the « Linked Products » tab of each product.
Key takeaway: used well, these suggestions raise the average order value without feeling pushy.