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.
Hang from the bar with an underhand grip, spaced just wider than shoulder width.
Pull up by brining your elbows to the back of the hips until chin is level with bar.
Slowly lower back to start position and repeat.
Swinging to get up.
Dropping on the way down.
Uneven grip.