Plot the route on your chart as always. Now put the plog aside, fire up Google Earth, locate your start point using the search bar (it accepts ICAO airfield identifiers), set the zoom level to a reasonable scale (there is an 'eye altitude' number which should initially be around 5-10.000' or so) and see if you can find your route by referencing the chart and cross-checking it with GE. Zoom in and out as required. Take particular care to identify all the waypoints that you planned to pass.
This way you know what the route looks like from the air, what waypoints on your chart are easily identifyable and what waypoints are not. And you might find a few other prominent features that you can use as a cross-check, but which are not marked on the chart.
More advanced use would be to put the route into an electronic mapping program (Your GPS, or something tablet/PC based), exporting the route, converting it to KML and importing it in Google Earth. You can then see your route overlaid on the terrain.
(This is something I occasionally do post-flight: Take the track log from the GPS, convert to KML, import in GE, set a zoom level so that everything fits on the screen, make a screenshot, crop it and mail it to my passengers. Nice memory together with the photos.)