“its really important to begin the negative portion by bending your knees, not by sticking you but out and leaning forward.”
Sorry but this is completely wrong - the first movement downward in the squat should be your hips moving backward i.e. sitting back. If you need a reminder of proper squat form think about your movement as you sit down on a toilet (sitting back) and note where your knees are in relation to your toes (behind).
This is what I have taped in front of my squat rack in my basement to constantly remind me of the proper squat form.
Look-up
Head locked back
Elbows under bar
Pelvic Tilt
Deep Breath
Push out Abs
Squat Back and Down -
Through tighness of hips
Arch out of Bottom
Drive Hips Forward
Let out Breath - Hiss
Look-up - your body will follow your eyes. Try this when you are deadlifting.
Head locked back - easy way to add lbs on your squat by placing your head in the proper alignment.
Elbows under bar - I have to actually lock my elbows under the bar and pull them in towards my body to keep proper back alignment.
Pelvic Tilt - ensure your pelvis is tilted back before starting the movement.
Deep Breath - fill your body with air.
Push out Abs - include filling your abs.
Squat Back and Down - sit back. This ensures your knees will remain behind your toes.
Through tightness of hips - This is for my wide squats.
Arch out of Bottom - first movement out of the hole. Another way to envision this is to throw (not literal) your head back.
Drive Hips Forward - As you are ascending you must drive your hips under the bar. The quicker you can do this the easier the lift is. Also try this while deadlifting.
Let out Breath - Hiss - Place your tongue on the roof of your mouth (remember your are full of air) and as you ascend be sure to let a small amount of air escape especially as you drive through your sticky point(s).
These are my personal reminders - yours may be different. I have video taped myself many times to determine my squat flaws and these are the areas that I need reminders on.