Position a plate on the ground. Setup by a machine or fixture where you can support yourself.
Put both feet on the plate with your toes pointed straight ahead.
With your knees slightly bent, make sure your back heels are off the plate.
With a neutral spine and your core braced, hinge at the hip and bring your torso to just above parallel with the floor and rest your hands on a fixture, barbell, or against the wall
In a controlled manner, flex/extend at the ankle through a full range-of-motion.
Maintain a slight knee flex throughout the exercise.
Full plantar flexion and dorsiflexion.
Conscientiously lengthen and shorten the calf musculature to control the movement.
At the top of the range-of-motion (full plantar flexion), think about driving your heel into the back of your knee.
Don't just press the balls of your feet into the floor.
Don't bounce yourself up. Really emphasize controlling the exercise with your calves.
Your upper body remains passive during the exercise.
*Tips*
Establish a strong mind-muscle connection and be deliberate with each repetition.
Experiment with different rep schemes and various time-under-tension protocols.
Don't actively point your feet internally or externally. This will have no real effect on the execution of the exercise.
You can effectively add weight by strapping a dip belt around your waist and attached a respective load.