biggest error for me, looooong time ago before the digital age, going out on a school assignment that needed lots of photos, taking trusty SLR being quite happy at getting around 40 shots out of a 36 exposure film to find later there was no film to develop....
digital age .. setting stoopidly long shutter speeds then not changing them for 'normal' shots
digital age .. setting stoopidly long shutter speeds then not changing them for 'normal' shots