Watch potential customers try out camcorders and you'll see that one of the first things they test is zoom capability. And why not? Unlike Hollywood movie directors who can place a camera wherever it suits them, you may be trying to get a shot of a grizzly bear from hundreds of yards away. Punching up the telephoto zoom can be the difference between fur and blur.
As you're zooming, however, try to keep the motion steady and measured. The zoom control on most camcorders is pressure sensitive, so pressing hard makes the lens zoom more quickly than it would if you used a lighter touch. Try not to zoom in or out (or, heaven forbid, both in succession) as fast as possible, unless you want in the end to nauseate your audience. If you can, practice your zoom once or twice before you actually begin filming.
When you're finished zooming, don't forget to turn off your camcorder's digital zoom feature. Unlike optical zoom, which reflects the actual zoom the lens mechanism is capable of, digital zoom involves the camera's processor, which interpolates the image and enlarges the pixels to approximate a higher zoom level. In essence, the camera is guessing what the higher zoomed-in image will look like, and it shows: Digitally-zoomed footage is highly pixelated, and it's often hard to tell what was originally being shot. Turn it off now while you're thinking about it, so you don't scold yourself later when reviewing your unexpectedly blurry footage.
Do You Hear What You Hear?
As you're recording, use headphones plugged into to your camera to ensure that the audio you're capturing is the sound you expect. Any pair of headphones will do, as long as what you are hearing is what the camera's microphone is picking up. You don't want to begin editing your footage only to find that the traffic noise you've grown accustomed to has obliterated the rest of your footage's audio.
It may sound like a hassle, but try to keep a record of what you're shooting. Professional shooters keep a log book to note what's being shot and when. Although you may not need to be as meticulous, a record of shots will come in handy when you're editing clips and can't tell if the footage is, for example, Alaska's Ruth or Holgate glaciers.