How to squat

I've spent a lot of time at the gym and I see a lot of mistakes when it comes to squats. There are many different kinds of squats but there are some basic principles that apply to most if not all of them. 

1. Hips should initiate the movement. Imagine sitting in a chair. When you sit down your hips move backwards into the seat.( this is a good way for beginners to start squatting ) This action brings me to my next point

2. If your knees are behind your toes, the power for the squat is coming from you Glutes and hamstrings. When your knees fall forward in front of your toes you are putting a lot of stress on your knees. Another good indication is that you will feel the weight in your heels. If the weight is in your toes it's wrong. ( this applies to leg press machines as well)

3. Keep your chest up.  Each person is shaped differently and will have different ranges of hip mobility  but despite your range, you want to try and keep your chest as vertical as it will allow. A tip to help with this is to keep your gaze above eye level. When your eyes fall your head tends to go with it and when your head falls, your back tends to go too. 

4. Stance. Because there are many different squats I'm going to focus on the basic squat. You want to be hip to shoulder width apart.  From my experience very few people can do a correct squat with their toes absolutely straight forward so turn them out slightly. Think 11  and 1 o'clock. Stick your butt out ever so slightly while keeping your chest up.