The key to sucessfully containing your pet really comes down to one thing, TRAINING!
For several years now we've been using the "Light Hands" or "Light Touch" method of training. The roots of "Light Hands" go back nearly 100 years. It started with horses and was then adapted for hunting dogs. It the late '90s Rich Weinssen took the lead in developing this "Light Touch" approach in electronic pet fences.
The idea is quite simple, start with a very light almost inperceiveable correction. By starting light you're not going to create stress. Dogs can't learn when they're stressed, so the warning tone combined with just a light tickle allows you to move freely about the yard and approach the boundry. As we approach the boundry the collar will beep, then deliver a light tickle. At this point we bring the dog back into the safe area. This is the beginning of the conditioned response that we're looking for.