I've been a user of TOPO! (by National Geographic) since it was owned by Wildflower Productions. So, I have the electronic database of all topo maps on CD-R for California, which is where I operate 99% of the time.
To use the military terminology, I do mission planning first. That means to electronically mark the route. In some cases, there are downloadable trail routes available, but most of the time I just trace out my own. Sometimes I will mark route waypoints, and these are recorded with lat/long that can be transferred as a route to my GPS receiver. I print out a full size map in color, and it shows the route with the waypoints. Then when I arrive in the field, I can travel with the receiver turned off if navigation is easy. If it gets more difficult, I can turn the receiver on and let it point me from one waypoint to the next. Having a printed map is essential since the screen on a receiver is extremely limited, and there are such things as electronics failures and battery failures.