After grabbing the bar, engage your lats before you even start pulling, and keep your traps and upper back pulled down. Your head should be slightly tilted back, but your torso should remain bolt-upright, much like you're doing a seated pull-up. Pull your elbows toward the ground with your back, not your biceps.Pull the weight down slowly, squeeze, and release it just as slowly. The only parts of your body you should be consciously moving are your elbows. If you start to lean back, you'll start recruiting your rhomboids, so stay upright.Once you know you can handle the weight with perfect form, you can start to put the pin lower. However, if you begin to move your torso or you start to feel your traps rise up, you know you've gone a little too heavy.