For city travels online booking is one of your best options. You can do all of your research, know exactly where you need to go and what you need to do ahead of time. You can plan everything in advance, making sure that you have enough time to comfortably fit everything in, and then make reservations all online. Another thing that you can get, so that you are better prepared for your city travels, is any number of city travel guides.
You can find them all over the internet, all you need to do is search for them based on a specific city. For example, Free New York City Travel Guide will bring up just that. In fact, it will most likely bring up many options for you. You can often find blogs describing the best kept secrets of the city, how to get there, and how to enjoy them on a budget. You can also find sites that tell you how to enjoy all of the things that the city is known for. Like in New York City, it will tell how to get to Central Park, see the zoo there, and then point you in the direction of the American Museum of Natural History, which is right next door.
Some guides will walk you through an entire day, and you follow their instructions to the T, down to how much you spend and how much time is dedicated to each location. Some people need that much structure and direction when they are in a new and unfamiliar place. Other guides work on suggestions, giving you a series of choices for any given day. This allows you to still stay within a certain outline of times and places, but gives you the choice of where to go and what to do. And then there are the broadly generic guides. They consist of a lot of Do Not Do This or Maybe You Should Try This. They are helpful, but some structure is recommended for a first time visit.
Whether you want everything laid out for you, some helpful suggestions to get your new city explorations going, or just a pat on the back and a Good Luck on Your City Travels, you can find all of these and more on the internet. Like with anything new, it is best to do your research first. Especially when going to a city for the first time, know where things are. Know where China Town is so you can visit it, and know where Hells Kitchen is so you do not stumble upon it at two in the morning.