Being able to perform free squats which is one of the easiest variations will give you an indication if you re ready to start trying single leg squats.
Single leg squat standing on box.
Perform 3 sets of 10 repetitions on each leg.
Land softly on the box in a partial squat position then stand fully upright.
Step back down to the floor to the starting position.
Stand on the side edge of the box and let your one leg rest in open space.
Get a box or a chair the lower it is the harder the box squat will be and stand on one leg facing away from it.
I f necessary the spotter can stand at the side place one hand on your wrist and the other hand just above the elbow keeping the knee of the working leg in line with the long toe squat down until your thigh is parallel to the floor.
Squat down until you are sitting on the box then push back up.