Picked an OEI technique some time ago in the SIM from a colleague. One was quite ashamed of not being trained to do so earlier, nor devising it on my own.
N1TLA.JPG
a) As the trust-lever is moved to idle, as a part of the shut-down drill, focus the eyes on the TL position indicator (white doughnut on the picture above). Observe its movement on the correct engine.
b) move the TL slowly, watching with your other eye the good engine's N1 - that they do NOT move, with sharp ears and sensitive pants towards any undesired change.
It is easily done with a two-phased movement: retard to 2/3rds, check the gauges and gut, if all ok then close the TL all the way.
c) do not let go of the retarded TL straight away, pause for one deep breath with the eyes on the instruments.
Rush is the ultimate killer. Tenerife, Spanair, Taipei, sadly many others.