Push straight back up, lifting your hips up and forward to lift toward starting position. From lower position, push up off your heels and lift the weight while maintaining good, proper and safe form. Use almost every part of your body while straightening your legs, and slowly, evenly move up.
Your back should stay straight. Do not let your spine curve throughout any part of the exercise.
Focus on using your explosive glutes (butt muscles) to get power on your way up without using your back.
Try to make this movement smooth, moving in one fluid motion to prevent injury and unlock the majority of your power.