"The experience of the ages shows that the sign of the cross has great power over all a person's actions during the entire course of his life. Therefore it is necessary to strive to root in children the habit of protecting themselves with the sign of the cross often, especially when receiving food and drink, going to bed and waking up, before departing somewhere in a vehicle, before leaving and entering any place; and they should not make the sign carelessly or according to fashion, but precisely, beginning with the forehead to the solar plexus, then to both shoulders, so that a proper cross is produced.... The sign of the cross has saved many from great dangers and afflictions."
- Elder Ambrose of Optina
Reference: http://www.pravoslavie.ru/english/47530.htm