Wildlife photography can be very rewarding as well as very frustrating. It frequently has as much to do with patience as it does with actual photographic knowledge and skill, but it is the challenge that makes it enjoyable.
Beyond the basics there are few technical things to know, and it is one of the areas of photography where equipment really can mean the difference between getting a shot and not getting one. Zoom or telephoto lenses, while not a must (some of my best shots were the closest), are valuable for most sorts of wildlife. Despite this, the closer you get the more likely you are to get a quality image with less camera shake, no haze or objects in the way, and more control on your angle and depth of field. The most important thing is to learn about the habits of the animal you are targeting, get out there and spend lots of time. Your wait will no doubt be rewarded eventually, sometimes with something other than what you were looking for surprising you.