In high end restaurants tips are more likely to be expected because the waiters are professionals. Here you should tip at least 10% for good service but only if there is no service charge on the bill. You should hand your tip directly to the waiter. If you are served by multiple people give the gratuity to the most senior waiter who served you. Make sure that the other staff who served you can see this and indicate clearly to the waiter who the tip should be shared between