Standing with feet hip-width apart, dig the big toe in each foot into the ground. 

Holding the barbell using a pronated (palm down) or alternate grip (one palm up, the other palm down). Hands should be outside hip-width apart.

Tighten the core as much as possible, imagining that someone is about to punch you in the stomach.

Drive the weight up by allowing the barbell to ride up the legs, focusing on the hamstrings contracting and doing all of the work, NOT the lower back. Squeeze the glutes at the top by performing a posterior pelvic tilt (pointing the tailbone forward).

Keep the core tight and back straight during the descent.