OHH! Magellan! That might be the problem! (Just kidding! I'm a Garmin
person!)
It's not an exact science at all! The closer you get, the more the GPSr will
jump around. I get close, (within 20 feet or so), then stop looking at the
GPSr and start looking for hiding spots. You'll get the hang of it after a few
caches!
Happy Hunting!