Stand on one foot, and lower into a squat. Continue all the way to the bottom of the squat (when your butt touches or nearly touches your heel), slowly and in control, then gently roll onto your back.
Roll forward, and carry your momentum to come back up onto your foot and stand up for one repetition.
Continue for the required amount of reps on one side and then move to the other.
Progressions And Regressions