These introductory verses provide the starting point for more specific commands. It is as though God is saying, "This is the foundation of good family and community relationships. Aim to be holy, to be different from other nations, to be clean in My eyes through your conduct of obeying My laws. This will separate you."
Note an interesting feature. God draws attention to the fifth, the fourth, and to the first and second commandments as His keys to accomplishing the activation and growth of holiness, first in a family setting and then its spread into the community. This indicates that in God's eyes—in terms of holiness and good family and community relationships—keeping these commands are the major guides and regulators, actually necessities, toward producing family and community success. They provide a foundation for regulating social relationships within both family and community.
Of special interest is the order God sets them in. Both honoring parents—and most specifically the mother, as she is mentioned first—and Sabbath-keeping are mentioned before idolatry. In terms of good family relationships, this is the order the child is introduced to them. In an infant or young child's life, mother is primary. Do not forget, God gives all of this instruction with one common goal in mind: to produce holiness and good family relationships.
Why does God say, "You shall be holy, for I the Lord your God am holy"? It is His way of pointing out to us, His converted children, that He Himself is the Model, the Standard, we are to follow in our child-training practices. As His children, He is the One we are to imitate.