There is more than just one of traveling in Hong Kong. Here is a list for consideration, plus there will be other entries to give a little history and more information about these methods of transportation.

MTR (Mass Transit Railway) - The MTR is essentially the Hong Kong version of the subway, traveling underground but above ground in some areas as well.. It will allow you to reach virtually anywhere, with a little bit of walking, and there are buses to take you to the places that the MTR does not reach.
Bus - There are buses that run throughout the Hong Kong region, both single and double decker.
Mini-Bus - Mini-buses carry roughly 16 people and will also take you throughout Hong Kong, though they will take you places that normal buses will not (more remote areas of Hong Kong).
Taxi - As in any big city, there are taxis for hire. There are three colors of taxis to be seen in Hong Kong - red, green and light blue. The red taxis will travel all over Hong Kong, whereas the green taxis are more for the northern New Territories. The ligh blue taxis are on Lantau Island, where the International Airport is located.
Ferry - An older way of traveling between Kowloon and Hong Kong Island, one can still board a ferry, especially the Star Ferry. For traveling to Macau and islands close to Hong Kong, there are ferrys that can be used for travel.
Walking - The good old fashioned way of travel.

Tourism in Hong Kong