Sounds patronising, so apologies for that, but have faith in both clock and compass, both have been serving travellers well for centuries and early aviators had nothing else unless you scrape the barrel and add the stars. With short legs an error has to be big to be significant. (1 in 60 rule)
Map study and more map study and typically 5 miles either side of track. Aircrew cunning; if there is a nav aid en-route, use it unless told otherwise, and even if so, it shows that the blinkers have a field of view beyond that of a toilet role. I always chuckle when I pass abeam a VOR clearly visible with no aircraft nav aids tuned into it. TACAN can give a distance if using DME.
Finally, I was on board a multi man aircraft during a students Nav Check sortie. The sortie ran on rails in terms of both timing and position and I thought it sure to be an 'A' pass. He got a C+ because he had not used the taught (leap-frog) procedures at all, and whilst a pass is a pass, there is clearly a game to play also and these days being top of the class can be the differance between getting a cockpit or not.
Have a map stored away that includes Diversion airfields well off the planned route. I have seen an aircraft 25 miles off track to circumvent a thunderstorm, again thinking bigger picture.