To increase the experience and turnover without pressuring the guest
Upselling has a bad reputation because many associate it with pushy salespeople. But in the restaurant business, good upselling is service: you help the guest to a better experience by suggesting what suits them. When it is built on professional knowledge and sincerity, the guest feels it as help, not pressure.
The best salesperson in a restaurant is the one who knows their menu and listens to the guest. A guest who doesn't know the menu appreciates a knowledgeable recommendation. You don't sell the most expensive — you sell what makes the evening better for that particular guest. That builds trust, and trust creates both good experiences and returning customers.
Timing determines whether a suggestion is perceived as service or disruption. A suggestion for an aperitif belongs at reception, drinks at ordering, and dessert and coffee when the main course is cleared. If you suggest dessert before the guest is done with the main course, it seems rushed.
Your knowledge of how food and drink work together is a strong sales tool. When you can explain why a particular drink suits a dish you give the guest a reason to say yes that is about experience not price. Professional weight makes the suggestion credible.
A no must be respected immediately. Pressing further ruins the atmosphere and trust. A friendly 'of course' and continuing the service shows professionalism. Good upselling is never pressuring a guest against their will — it is making it easy to say yes to something they actually want.