Set-up: Find a preacher curl apparatus with an EZ bar. Grasp the bar using a narrow underhand grip.
Lift: Keeping the elbows at your sides and your eyes forward, curl the bar up to your chest. Lower the bar under control. Do not let your upper back round over - consciously pull your shoulder blades together to provide a stable base for your arms to pull from.
Emphasis: Do not swing - keep your core tight and a neutral spine.