Reddit reviews Not of This World: A Treasury of Christian Mysticism (Treasures of the World's Religions)

My personal suggestions, study whatever you can on the following:

1. The German/Rhineland Mystics and those they influenced: Meister Eckhart, Johannes Tauler, Henry Suso, John of Ruysbroeck, Nicholas of Cusa, Jakob Boehme, and Angelus Silesius.
   
   
2. Greek and Desert Fathers: Dionysius the Areopagite, Maximus the Confessor, Evagrius Ponticus, St. Isaac the Syrian, anything on Palamism/Hesychasm, anything on theoria/theosis.
   
   
3. Manuals for practice: The Cloud of Unknowing, the Philokalia, Abandonment to Divine Providence by Jean Pierre de Caussade, the Imitation of Christ by Kempis, the Theologica Germanica, the works of Theophan the Recluse.
   
   
4. The famous Carmelites of St. Teresa of Avila and St. John of the Cross.
   
   Two decent collections on Christian mysticism worth checking out are Bernard McGinn's The Essential Writings of Christian Mysticism and James Cutsinger's Not of This World: A Treasury of Christian Mysticism.
   
   Of all the above, the two ultimate mystics in my opinion are Meister Eckhart and Dionysius the Areopagite, and the two best works on practice are the Cloud of Unknowing and the Philokalia. Studying those four areas would be the best in my opinion.