Widen your stance about half of your foot width. Set your knees better by pushing them out and keeping them over the mid line of your feet. Get tighter before each rep (including your unrack. Break at the knees and hips at the same time, but make sure the knees are done moving fotward by the time you are halfway down. Push your hips back further on the way down. Stop moving your head around and keep it (and your eyes) fixed at the same place the whole time. Film every set you do, watch the footage as soon as you are done, and correct issues on the next set.
If possible, use a different squat stand/rack that will allow you to position your feet under the bar better.