The "map to ground" thing is to prevent guessing at which of the 10 little roads you can see is most likely the right one - rather than looking out, seeing a feature and convincing yourself it's the right one, you go:
Clock - how long since the last known point?
Map - at my planned or known groundspeed, how far should I have come on the map and what should I see at that point?
Ground - look out and find the expected features, using big to small. Orientating the map so track is up will help with that too.
Another hot tip in my opinion is to ensure you have an identifiable feature very near the start of each leg so you can positively confirm you're on track to start with even if you've manouevered off track while departing or carrying out the turn at a turn point.