The first thing to do when booking a restaurant reservation is to call ahead as much as possible and note down when it is you want to come, how many people will be coming and whether or not any advance payment is required. Most restaurants will not take bookings that are for more than a few days in advance so be sure to clear these confusions out before going ahead with anything final.
You might want to end off the perfect date or time with that special someone by going to have dinner at the best of places the city has to offer, but it is important to remember that these places are always where the most rush is. Staying flexible will allow you to have ample time to eat and relax if you avoid prime time, especially for dinner which is around 7 to 7:30 pm. Try going a little later or even earlier if you have to.
Stay Calm and Respectful
Debating on the phone as to why you are not able to get a seat at the time you have specified is of literally no use because the phone attendant does not have any personal benefit of you getting the reservation or not. All they can do is tell you about the situation and asking whether they can be adjusted for later on or earlier is a good way to go about it.
Cancel if Not Going
Most restaurants will be kind enough to make a reservation for you without taking any advance payment, but in order to show mutual courtesy, it is a recommended that you cancel your reservation if you change your plans ahead of time. This will allow the restaurant to accommodate someone else and not have to sit idle waiting for you.