1. All traditional training in art involves drawing by copying from nature and then copying the works of Old Masters. Ideally children would do both but precisely what they try to draw depends on how old they are. Very young children could colour in line drawings based upon traditional forms - I illustrated a couple of books with this in mind, see Meet the Angels and God's Covenant with You. The more sophisticated might be able to try some tonal work on a copy of a baroque painting. A great start for anybody would be gothic or Romanesque illuminated manuscripts. These are line drawings with limited modelling. They are great fun to draw and my experience is that Catholics relate to these Western icons more readily than to Eastern iconographic forms. If you to get hold of examples type 'psalter' into the Google Images search engine. You don't need to feel bound to sacred imagery. The psalters of this period contained pictures of the everyday life at the time. All the examples shown here are from the Westminster Psalter. I have mentioned before elsewhere, how the students in my classes at Thomas More College seemed to thrive in studying these images. So much so that the summer school offered for adults will focus on this style of image as well.
Drawing from nature, even for the most simple subject is more difficult. When the child is prepared to gie it a go start with simple but interesting forms that don't require the child to summarise. So drawing a tree is very difficult, because it presents the problem of how to deal with thousands of leaves, but drawing a single daffodil is a bit easier.
2. Pray the Liturgy of the Hours in the family. This is perhaps the single most important item. Where possible the father, as head of the family, should lead the prayer and it should be sung. Wherever possible the psalms should be sung and the prayer should be oriented towards sacred image or images. o I have written about the creation of a domestic church and the importance of the father in family prayer, here. I have written about how to create an icon corne as a focus for prayer at home, here. I have written articles about the importance of the liturgy of the hours in general, here. Interestingly, I made some suggestions to this person who asked my about how he might sing compline with his children. I sang some very simple tones which he recorded on his laptop so that he could learn them (they were from the selection developed for the students to sing at the liturgy at Thomas More College of Liberal Arts). Then I showed him how to point any psalm so that any of these tones could be applied to them. He told me late that his children loved to sing the psalms and were competing for turns to sing on their own.
3. As soon as possible learn to chant. Even if it is the simplest form chant the introduction of the child to the eight modes that we get in chant, I believe. The intervals and harmonious relationship that are traced out in music impress upon the soul the essential patterns that comprise the beauty of the cosmos and which ultimately point, to use the phrase of Cardinal Ratzinger in the Spirit of the Liturgy, to the 'mind of the Creator'. Conventional music contains only two of the modes and so if the child is only exposed to the major and minor keys, no matter how beautiful the music, they will have a limited education.