I tend to use airway intersections rather than anything else for VFR. For example instead of trying to enter a waypoint for Reading, I'll just use LINDY which is in the GPS.
I have made many errors over the years entering wrong lat and long info - normally related to entering EAST instead of WEST which makes a big difference
I distinctly remember doing this one time, checking, double checking and I still had it wrong. It was only when it became obvious that it was wrong that I sussed out why.
I suppose it is like proof reading your own typing.