The folowing tips are in no particular order.

Always give your equipment the once over and ensure the camera lens is clean and batteries are fully charged before filming, if your camera uses DV tapes have you got enough. Ensure you have all the equipment you might need for a particular shoot, no good going with bare essentials and finding you forgot something, write down a checklist of what might be needed.

Most cameras come with optical and digital zoom, avoid using the digital zoom option, poor film quality is all you will get.

If your camera has image stabilization then generally it is best to have the option OFF when using a tripod, and turned ON when using it hand held.

Avoid using long play on your camera, this reduces film quality and if you use DV tapes then dropped frames are a possibility.

At all times try to use a tripod, this will ensure your film  does not look shakey, and is useful when panning or following a subject to give a nice smooth shot. It also can free up your hands if it is static filming to concentrate on something else.

Use an external light source if possible when filming at night or when the light is fading, avoid using the camera light, not only does drain your battery but they are not very effective.

Choose a microphone that best suits the subject matter, Omni-Directional Microphone for when you want to record sound coming from any general direction, use an Uni-Directional Microphone or Shotgun Microphone for more precise recording of sound. Clip-on or Lavalier microphones are mainly used for interviews, can be wired or wireless, it is important to monitor body movement or moving objects while recording.