Try to squat as low as possible with no pain. It's very important to keep your weight in your heels so that your knees never come in front of your toes (to protect your knees).
The lower the better to get full Range of Motion to keep your joints healthy and involve the most amount of muscle and effort to get the biggest benefit from the movement. If you have knee pain or trouble squatting, find a low chair to aim for. Tap it and come back up!