Ensure your knees bend over the bench and the lower pad is against your lower shins.
Extend your legs to a point just before they are fully straightened.
Lower back to the starting point in a controlled manner.
Extending the legs fully.
Feet pointing too far outwards or inwards.
Using momentum to bring the weight up or down.
Start by adjusting the seats depth to allow your knees to bend over the bench when your back is firmly against the seat. Sit down and position your lower shins against the pads.
Begin the exercise by extending your legs upwards to a point where they are almost straightened. Then in a controlled manner lower them back down to just before the starting point to avoid clashing the weights. Use the handles on the sides to stabilise yourself when performing the movement. Repeat for the desired amount of repetitions and then gently rest the weights back down.
Control the weight throughout the entire movement where you avoid kicking your legs up for momentum and free falling the weights on the way back down.