Hip extensor strength is crucial for a healthy spine (and knees, and ankles for that matter).
So if your hip extensors (Butt) is too weak to jump right into squats, begin these basic butt-building-block exercises.
1) Start with both hands on the bar for stability with your body in a spine neutral position. Your stomach should be tensed, with your chin slightly elevated.
2) Extend one leg straight back and hold at the “6:00” position. Hold this for 10 seconds
3) Stand to the side and left your outside leg straight out to the side to the “3:00” position.
4) Once you have mastered these three positions, repeat with your foot turned out away from the body. This simple change further isolates the glute(s) and will intensify the exercise.
After you have mastered the variation of this exercise, add resistance bands or tubing. Be careful because a little goes a long way.
After you have mastered all these steps, you are ready to progress to a REAL squat; http://www.backoutofwhack.com/wp/exercises/low-back-squats/