Ensure the handles are slightly in front of your chest and aligned with the mid chest region.
Push out to a point right before your elbows are fully extended.
Retract back in a controlled manner just prior to the starting position.
Elbows flared at 90 degrees.
Wrists losing alignment with forearms.
Back losing contact with the padding.
Lie flat on a bench, with your arms straight over your shoulders, holding dumbbells.
Bend your elbows until your arms are bent at approximately 90 degrees.
Extend your elbows back to the start position and repeat.
Moving elbows around.
Using excessive momentum.
Rushing repetitions.