This has become an ongoing problem with my GPSr. What do you folks think?

All to often I try to find the exact location before I start looking. When I find the location Girlmate has usually already found the cache. When I look at the accuracy of the GPSr it can be usually +/- 20 ft. frequently it is more than a 40 ft radius that the cache is in. I have A Garmin 60c. I wonder if the problem is the operator, Any quick fixes that you suggest and Yes the WAAS is on.