Lie your child on their back.
Encourage the child to grasp your thumbs. Then, hold their wrists with your hands.
Encourage the child to bring their head to the midline. Ensure that the child first bends their neck and body when starting to push themselves up towards sitting.
Help the child with the movement only as much as is needed. Maintain interaction with the child.
If the child can, you can bring them down to supine the same way.
Ensure that their head does not drop back.