It is very, very difficult to get to that point. While God reveals himself to some rather early (Elder Sophrony, for example, experienced it as a child), most people will spend decades and decades battling the passions before reaching glorification. Of course, not everyone can receive this gift, because God only grants it to those whom he sees would benefit from it and often benefit those around them (1 Corinthians 12:26). The hermit at 3:00 in this Youtube video speaks a bit on it :
youtube.com/watch?v=Ap7kreDRzgQ
If one’s spirit draws him to attain such perfection, then he should first learn noetic prayer, under the spiritual guidance of someone who is at least illumined. Noetic prayer, as well as making one a “temple of the Holy Spirit”, allows us to see all of creation how it truly is (St. Maximos the Confessor speaks on this in his
Centuries), rather than under the shroud of delusion.
Of course, it seems that most people who receive glorification never actually focus on attaining it. Their focus is the casting away of sin in its entirety, the acquisition of complete dispassion, and unceasing prayer. That is, they seek to love God with their whole being. Of course, those who receive a permanent state of glorification (as opposed to those receiving a temporary form), often pray for it to be taken away simply because the feeling is, while indescribably joyful, almost unbearable - as if they would be consumed at any moment (which is why Orthodoxy teaches that heaven and hell are synonymous - consuming light and consuming fire are points of view depending on the purity of the soul).
If you have great interest in the subject matter, Fr. John Romanides has a book called
Patristic Theology that really examines this subject in greater detail, showing its importance in not only the Church, but the Old Testament as well. Theosis is central to everything Orthodox.