Keep a neutral spine throughout the movement and avoid jerking motions. Your pelvis mostly performs the motion along with hips, your back leg should not move much one you have got into position.
Get in a Staggered Stance and slightly then allow bend in the back leg.
1. To begin the stretch press your hips forward until you feel a stretch in your thigh.
2. Hold at this position for 20-30 seconds then alternate leading legs. Repeat both legs 2-3 reps.