Ask yourself these simple questions:
- Am I feeling the pull in the right place? Is the exercise putting stress on the muscles I'm targeting or is the strength I need coming from elsewhere?
- Can I control the movement of the weight? If you're relying heavily on momentum to complete the reps, this only increases the risk of injury. You should be capable of staying in any position during the rep, even the most difficult one, for at least 2 seconds.
- Am I utilizing the entire range of motion? Never sacrifice correct form for the sake of lifting more weight or finishing more quickly. Half-finished reps don't do you any good. Reduce the weight or the number of reps.