1. To be safe, a preferred choice of doing this exercise is to be inside a squat rack. For starters, take the bar onto a rack that matches the height of your body. After you have reached the desired height and bar has been set, begin to pull yours arms up under the bar while having your elbows high and the upper arm a little above parallel to the floor. To make sure you have total control of the bar, put the bar on top of the deltoids and cross yours arms.
2. Pull the bar off the back by using your legs first, while simultaneously having your torso straight.
3. Walk away from the rack and have your legs positioned with a shoulder width stance with your toes pointed out a little. Be sure not to look down during this exercise, as this can cause you to lose your balance along with not keeping your back straight. This will be your starting point. (Tip: Although you can use any of the three different stances shown in the foot positioning section, we will be using the medium stance, for that stance best targets overall body developing).
4. At a slow pace, start to lower the bar while bending your knees. Keep a straightened posture always with your head up. Keep going down until there is an angle between your upper leg and calves that become a little less than 90 degrees. (here is the position where the upper legs are below parallel to the floor. Remember to breathe in during this point of the exercise. Tip: To assure your are doing this exercises correctly and not putting stress on your knees, make sure the front of your knees are within a straight line that of your toes. If your knees pass your toes, you are doing the exercise wrong.
5. Start to raise the bar as you breathe out while  pushing the floor by use of your middle foot, along with keeping your legs straight and going back to the original start position.
6. Do the recommended number of reps for this exercise.

Caution: Like most exercises, this one is to be taken seriously. If you suffer from back problems, other versions are recommended such as the dumbbell squat or the leg press. If your back is healthy, make sure your form is right do not slouch your back forward, as this may result in an injury. Be aware of the amount of weight being used. The golden use, if your not sure, it’s best to use less weight. This front squat exercise if a safe one, if done correctly. This exercise is used by advanced athletes.

Alternative: There are a couple of different stances that can be used for this exercise. It all depend on which muscle you want to focus on. Using a small sized block under your heel is a good way to help your balance.

How to Front Squat Video