Prepare the appropriate weight taking account of your fitness level. Grab the barbell using an overhand grip slightly narrower that- shoulderwidth. Your feet are shoulder-width apart and your torso is firm. Hands holding the barbell are loosely hanging down.
From the lower position lead the motion by bending your elbows, in an upwards direction, pulling your hands closer to your neck area. Elbows go apart and upwards. Your wrists are bending slightly in the direction of the barbell motion meaning that in the upper position they go down. Exhale while overcoming the resistance (towards your neck, upwards) during the motion and inhale while returning to the starting position.
Make sure your torso is fixed and do not bend at the waist. Keep your pelvis in a neutral position. Avoid involving the trapezius muscles (lifting arms up towards your neck) while doing the motion. Avoid uncontrolled motion downwards. Control the motion downwards slowly up to a full stretch and then inhale.
Start with lighter resistance to master the technique well.