1. Mobility
A simple test to see whether you should in fact even be squatting is to do a simple squat without a bar or with a broomstick overhead.
If you fold in half and struggle to keep you heels on the ground with your body upright, you may want to reconsider even doing squats until your mobility has improved.
The three key areas where you will need adequate flexibility are your ankles (calves/achilles), hips (hip flexors and adductors) and your shoulders (lats, triceps, delts, traps and chest) to ensure you can hold the bar in the right position.