If your GPSr has waypoint averaging, I would recommend setting it in place for about 15 minutes and letting it average. If it does not have that feature, I would return to the spot of the cache several different times (and at different times of the day) then average your readings. This is probably more than a lot of cache hiders do, but should improve the accuracy.

Yup, The SporTrak Map automatically does Averaging once it sits still for awhile. 10-15 minutes of averaging should do it. I also try to mark the spot on at least two if not more occasions – While scouting, while finalizing cache placement, when placing the cache, etc. Again, this is often more than many cachers do but this is just one part of what makes a quality cache! Looking forward to the hide (although it may be awhile before I get down there )