I competively Olympic lifted (Clean and Jerk, Snatch) for some time and have also torn my Labrum in my hip, so I know a little about the hip and extenders. First off is breathing technique, do not take a deep breath into your chest, but rather breath down into your stomach, this allows you to use you diaphram to support your core meaning more muscle recruitment and stability. As far as hips go, try goblet squats and at the bottom of your range use your elbows to push out your knees, this will help develop solid hip mobility "in the hole" until you are ready to go to back squats. A glute ham raise back extension will also come in handy!