How to do a proper barbell squat:
1. You should stand with your feet firmly grounded on the floor, about shoulder-width apart.
2. Place the barbell on your back, just above your shoulders. (It should be directly on your trapezius muscles.)
3. Barbell in place, it is time to slowly bend into a squat. When do you stop? When your knees pass the 90 degree mark. That’s right, full squats when your hams almost touch the calves are the way to go.
4. You should then contract your legs and buttocks while stabilizing your body.
5. At this point, you should stand back up. Slowly.
6. Continue until you have done enough repetitions to complete the set as you’ve planned. Remember, at no time should you feel like you are not in control of the weight that rests on your back: if you feel unsteady, cut your set short.
7. Also remember to keep your knees in line with your toes; this will help you to achieve the proper posture for this exercise.