Make sure your box is high enough so your lower back does not round in the tuck position. Better use a box too high than too low!
Point1 foot a tthe time. Keep your ankles together. Do not move the leg! Nothing but the toes of the immobile foot touches the wall.
Isolate the movement into 1 leg at the time. Align the working leg with the already perfectly aligned hands, shoulders & hips. Elevate your scapula fully at all times. Do not round your back or slip into a posterior pelvic tilt when you bring the leg back to the wall.
Scapular elevated at all times. Look at hands at all times. Walk as close as possible to the wall. Do not allow your stomach to touch the wall. Feet only!