Once you get the mapsource product installed, download the latest updates at Garmin. We'll Take You There.™
. Also install google-earth, which integrates nicely with mapsource (you can send waypoints and tracks to google-earth).
I love to mark the positions of blinds, fishing holes, boat ramps, and most importantly, where my truck is parked on long hunts/hikes. Having a GPS in the dead of night is a great way to get back.