By Philip De Vere (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
The Holy Garments were a necessary part of the Priest duties as any other article of the tabernacle service. The garments were symbolic of being set apart for God's work. Aaron and his sons were required to wear the garments into the tabernacle so that they would not incur sin and die; Golden bells were attached to the hem of the Garment so the people would know the High Priest was still alive, as he preformed his Holy duties.
The Ephod was inscribed with the names of the 12 tribes of Israel to remind God of the tribes whom he had made a covenant, as long as the priest bore the names of Israel on his shoulders the Lord would not forget to be gracious to Israel.
The Breastplate was also used as a function of remembrance, it contained the 12 tribes of Israel as well, in addition it is called the Breastplate of Judgement, it contained the sacred lot, the Urim and Thummim, worn above Aaron’s heart it would remind Aaron and God that justice originates with God and is maintained by God.
The Mitre was placed on the forehead of the High Priest it was inscribed with the words Holiness to the Lord. The Mitre was on Aaron’s head continually so that the children of Israel would be acceptable to the Lord. It was a reminder of consecration and the importance of approaching the Lord in Holiness
Without the Holy Garments the Priest offerings were invalid, and the Priest was like a stranger or non-priest, and he is not serving in the Priesthood; but the stranger or non-Priest is sanctified by the Holy Garment.
The Bible says we are all Priests and should be set apart. You should be wearing The Breastplate, The Ephod, and The Mitre. You should have something on your body to Indicate who you are, and whose you are, and who you believe in at all times, remind Jesus of His covenant with his people, Lets look forward to God's return.