Two checking / routinized tips for the basic tester:
  • Not doing something – it should 
  • Doing something – it shouldn’t

Two  testing / bespoke tips, for the advanced tester:

  • Doing something – it should
  • Not doing something – it shouldn’t be doing

See also What if – and Does it Matter Testing AND Checking 

3 types of bugs by Andy Glover @cartioontester

3 types of bugs by Andy Glover @cartoontester