Aaron was the first high priest and his sons were made priests. The tribe of Levi also worked in the tabernacle with Aaron. There were special clothes made for the priest. (ch. 39) The priest wore a turban on his head, also called a mitre. (39:30) There was a gold plate on the front that said HOLINESS TO THE LORD and was tied on with a blue cord.
The high priest wore an ephod (looks like an apron) that was made of gold, blue, purple, and scarlet thread, and of fine woven linen. It had shoulder straps to hold the pieces together. They were engraved pieces of gold with onyx stones on the shoulders as a memorial for the sons of Israel. (39:2-7)
(I briefly went over who the 12 tribes were)