To keep young children warm, wear leggings(socks attached) and tight fitting long t-shirts tugged into the leggings. You need to trap the heat inside the body. For the head, it is good to have a woollen cap.Once you have done this step, all other layers added on can vary according to the temperature.A scarf is very versatile and if too cold, it can cover neck, ears and nose. All the small parts of the body will turn chill very quickly so this is useful to have.