Kadosh

Kadosh (set apart) often translated "holy" or "sanctified"

Set Apart for GodThe Hebrew word kadosh means "set apart". It is usually translated, "holy" or "sanctified".
There are four ways to be set apart for God.
VocationThe first way something can be set apart for God is if God simply declares that the thing is special. The first time the word kadosh occurs in scripture is when God sets apart Shabbat as different from the other days of the week (Genesis 2:3). God later sets apart the days of Pesach as different from the other days of the year (Exodus 12:16).
Nothing in the Tabernacle or priesthood was set apart simply because God declared it so.
People can be set apart for God in this way. Sometimes this is dramatic, such as the calling to be a prophet, but most people do not experience God asking them to do so many specific things, or to be so isolated from society.
There is no ritual done to things that God declares to be set apart for him. Prophets are called but never anointed.
Even though we are not all prophets, it is true that God wants us to fit into his plans, and this usually means God sets us apart for his purposes by having plans for the "big decisions" of our lives such as where to live, what career to have, and if and when to marry. The English word for God choosing these major aspects of our lives is vocation.
Our vocation is not necessarily the work and life we find most pleasing or natural. Moshe never claimed to enjoy shepherding the Israelites. Jeremiah wasn't thrilled about being a prophet. Sha'ul was not talented at public speaking. Yochannan the Immerser had doubts about the message he was called to proclaim. Ya'akov wanted fewer wives than were in God's plans, and Solomon wanted more.
It is also true that we can mess up our original vocation, yet through God's mercy still be part of his plans. God hates divorce and oath breaking. If we are married or committed to an employer, we cannot use the concept of vocation as an excuse to change our situation. God's plans are in some ways flexible, and scripture makes clear that God will work within our vows even if those vows were not part of his earlier plans.
We should all know as much about our vocation as God is willing to reveal. Sometimes all we are told is, "Be patient."
IsolationThe second way something can be set apart is to be physically isolated from the world. Moshe was told that the place with the burning bush (which later scripture makes clear refers to all of Mount Sinai) is holy ground (Exodus 3:5). The curtain hung up as the final wall of the Tabernacle's innermost room made that innermost room so set apart from the world that entering it would kill even the priests.
There is no specific ritual to set something apart physically, but it is necessary to be specific about borders. One aspect of the tallit's symbolism is that within the borders of that prayer shawl is a place especially set apart for God. Some people, at certain points during the service, may even raise the tallit up to be like a tent around their head, emphasizing to themselves that in worship they are alone with God.
People can also use physical isolation as a way of being holy. Messianic Judaism has few, if any, permanent hermits. But events such as prayer retreats are common, where people escape from the routines of normal life and isolate themselves in a place of prayer for a few days.
DedicationLeviticus 27:28-29 tells us that people can dedicate items to God, and these dedicated items become "especially holy". People cannot be dedicated, for anything living that is dedicated must be killed. (Thus Samuel's mother, who dedicated him as a baby, was following an idea from her own mind and desperation, contrary to Torah.)
We are not encouraged to dedicate items to God. The Hebrew word translated "dedicated" is in other contexts translated "cursed" -- perhaps the best translation is "doomed".
Nevertheless, there are some things that are set apart to God as tools in his hands. The furnishings of the Tabernacle were anointed with oil and blood and were "especially holy" tools of worship.
Are people ever set apart in this third way? In some sense kings and priests were; their calling is more than a vocation: they became tools of God. Everything they did, each day, must be with God. For kings and priests God has chosen more than the "big decisions". And if they act contrary to God's specific plans it is at best a waste of time, and at worst a disaster for the entire community.
Kings and priests were also anointed, since they were tools of God.
Tools of God are "especially holy", which among other things means that their holiness is contagious. Holiness can spread by transmission.
Whatever touches the Tabernacle's altar become holy (Exodus 29:37). Indeed, this is what altars did -- they set things apart for God, so that an animal slaying changed from slaughter to sacrifice.
But being set apart does not spread to people by transmission. God made it clear, multiple times, in scripture, that a criminal who grabs hold of the altar gains no safety or benefit. Aharon was set apart by his ritual of anointing, not by the special clothes he wore.
People are never "especially holy". No one can make someone set apart for God by touch. But priests and kings can transmit other spiritual characteristics by touch, as in the Tenach's rituals about priests transferring guilt by laying their hands on the heads of animals, or the New Testament accounts of God's Spirit being transmitted to new believers by the laying on of hands. People were healed by touching Yeshua's tallit (Mark 5:30), or by touching handkerchiefs from Sha'ul (Acts 19:12).
There are no rituals about people gaining holiness by transmission, since it does not happen.
CommemorationRemembering things can set them apart. (Recall that, in scripture, remembering something is about prioritization and action.)
Remembering God's commandments makes us set apart (Numbers 15:40). Remembering Shabbat keeps it set apart (Exodus 20:8).
We too can set things and people apart for God by remembering them before Adonai -- by asking that God actively make his will for them happen when it seems like God's will is dormant, or by asking for God to live up to covenant promises he once proclaimed. We do this all the time: it's called prayer. Thinking of prayer as remembering things before Adonai helps us understand why only prayer that is aligned with God's plans produces results.
Seeing GodAccording to Hebrews 12:14 holiness is necessary to see God. It should not surprise us that our flavors of holiness help us see God in a different ways.
If we resist our vocation we will not see God "enlarge our boundaries" (1st Chronicles 4:10) as he desires.
If we avoid isolation we will not hear God speak in a "still, small voice" (1st Kings 19:12).
If we shy from our priestly dedication we will not see God "show forth the virtue of him who has called you" (1st Peter 2:9).
If we neglect commemoration of God's plans in prayer, or if we do not "remember from where we have fallen" (Revelation 2:5), then we will seldom see God act in our lives.