Use a workcycle, whatever it is they teach you. Practice this at home over and over (visualise). Walk around your back yard quacking to yourself till you can rattle it of without thinking.
Clock - Map - Ground
Big to small (features)
Natural to man made (big hills don't move, but houses, windmills and silos might)
Works a treat, use the GPS to back up YOUR nav, not the other way round...
Remember also anyone with a grudge and some knowledge can get gear from an electronics store to jam GPS signals. Lots of punters will be caught out the day it happens.
