Sit on a chair sideways, with your legs next to the chair.
Keep your toes pointed up and forward (or slightly to the center, never outwards).
Start the movement from the bottom to the top!

1. Stand up by trying to pull your body over your toes with the inner leg (closest to the chair).
2. Sit back slowly

Tip:
Try to grip the ground with the side of the outer (small toe) side of the sole closest to the chair, and do not let the big toe ball touch the ground.