The following video, made by the owner of Midwest Mountaineering, Rod Johnson, is a brief overview of the components required for successful wilderness navigation.
The map, the compass, the altimeter and the GPS must all be used in conjunction to one another. A climber should never depend solely on one of these items, but must practice using them as complimentary tools.
The best time to practice with navigation tools is when you need them the least. When the weather is good and it is possible to see everything, then there is little need for these. But when the weather is good, it is also possible to see what real-life features look like on a map. Understanding what the real-world looks like vs. the world in a white-out when you are completely reliant on your understanding of your tools is incredibly important. If you can get your systems worked out in perfect weather, then you'll be ready for it when things are less than perfect...
Jason D. Martin