Keep your weight back on your heels throughout the squat. Do not shift your weight onto your toes. Always move in a controlled manner. Do not bounce or jerk your body in an attempt to gain momentum. Repeat the squat until you are too fatigued to continue.
Beginners can practice their squatting form by literally sitting into a chair and standing back up.
For greater intensity, do the squat while holding dumbbells to the front of your hips. Keep your lower leg straight and bend your upper knee to a 45-degree angle. Let your top leg come across your body and rest on the floor in front of you. Very slowly raise your lower leg straight up toward the ceiling while squeezing your inner thighs together. Keep your lower foot flexed throughout the lift.