Getting a reservation is important for most moderate to high-end, sit-down restaurants. While many restaurants clutch a few tables for walk-in customers, the only real way to be assured you'll be seated when you show up is to make a reservation.
Call a restaurant for a reservation just before dinner service begins. In some restaurants, no one comes in to answer the phones until later in the afternoon.
Adjust reservations to include additional guests. You ought to never show up for a reservation with more people than you originally indicated, because the restaurant may be entirely booked and might have trouble obliging additional customers. considerably less numbers should also be reported so that the restaurant can fill up the additional seats.
Call to inform the host or hostess that you are running behind if you will be more than 15 minutes behind schedule. Restaurants need to be able to organize their tables and seating plans throughout the night, so it is only considerate to give a fair warning.
Cancel reservations as far ahead of time as you can so that the restaurant can re-book your table. Canceling at the last minute is inconsiderate of the needs of the restaurant and other patrons who want to take your table.