For all radio navaids I use SID (Select/Identify/Display). So - tune your aid, ident it then check the display:-
VOR - check that the inbound to the VOR displays correctly with the bar centered and TO displayed, move the OBS 5 degrees, should get half deflection, 10 degrees and the bar should go full deflection (in the correct direction), check FROM as well if being thorough.
DME - check sensible distance
ADF - Needle pointing sensibly, check it stays sensible whilst taxying.
Use SID in the air as well whenever you use an aid.
For GPS - they will have their own checks which you should familiarise yourself with, but I will always check that the map display is sensible.
But as IO540 says, best is to find an instructor who takes all this seriously!
Last edited by foxmoth; 29th October 2011 at 22:18.