Position
Plant your feet firmly on the floor or braced on the machine. Set the seat height so that your arms are about parallel to the floor when holding the handles. Place your back and head firmly against the bench with a natural arch in your lower back. Pull your shoulder blades tightly together and hold them there throughout the exercise. Use the foot pedal to get started so that your arms are straight but not locked, your elbows rotated out, and your wrists in neutral.

Technique
Bend your elbows. Bring your arms back, keeping them horizontal with your elbows and aligned with your wrists. Bring your arms back until your upper arms are almost straight out to the side of your body. Contract your chest, and push your arms forward all the way to the start position. Keep your chest tight, shoulders relaxed, and elbows slightly bent at the end of each rep. Repeat.