For those following along, Disert Paths has also been running a series on Christian mysticism. I have not yet interacted with those posts and wanted to pick up on some of those thoughts.
After Dr. P. showed a basis for mysticism in theology and exegesis, he continued to my favorite post in the series, Methods of Encounter. He has lots of good recommendations there, from meditative prayer to fasting to the essential but underpracticed discipline of internal silence. My own most common practice is meditating on a Scripture reading. How is this different from simply reading Scripture? That depends on how you normally read Scripture, I suppose. The meditative reader stops and ponders, puzzles and prays. Meditation on Scripture wrestles with the passage a little bit, not setting the goal of achieving a conclusion but aiming to make sure that every facet has been seen and understood, its thoughts being made part of our own thoughts. A meditative reading does not see Scripture as information alone, but also as the life-giving food which God gives us to sustain us (Deut 8:3, Matt 4:4). The mind is active, questioning and probing, but is not permitted that detached arrogance over its subject which is the mind's peculiar temptation. The mind interacts knowing that it may be required to grow and transform to encompass the thoughts of him who says "My thoughts are not your thoughts, neither are my ways your ways." (Isaiah 55:8)
For what it's worth, I find that meditational Scripture reading is among the most practical and well-grounded approaches. In contrast, an approach of mentally entering a spiritual realm hoping to hear the voice of God has certain risks (as Dr. P. has mentioned) and temptations along with it. This world is a spiritual realm already, we just tend not to notice. If you want to hear the word of God plainly, you've probably already got it on your nightstand or bookshelf and it serves as a steady and grounded focus for meditation. Trying to receive a special revelation of the word of God leads to a temptation to manufacture an experience or revelation, a temptation to self-deception in mistaking your own thoughts for God's (Jeremiah 23:16). Meet God at the word he has already spoken and be content with it. If you happen to hear more, remember to test what you have heard (1 Thess. 5:21), not receiving it uncritically, though still holding on to the good. Meeting God in a companionable silence or a reverent silence also has much to recommend it.
Dr. P. included a link in his post to a site that explains meditational reading well. I recommend the site, but it does remind me of one of the "problems of mysticism" I forgot to mention: the enfatuation with foreign languages and obscure terms unfamiliar to the average reader. I remember enough of my Latin that this site doesn't bother me until it comes time to recommend it to the general reader. Likely the writer is just steeped in a culture where that is acceptable. But for those just passing through, the whole "dress it up in fancy phrases, preferably in Latin" thing can be "off-putting" as they say. It helps recall the ancient roots of the practice and the site has a good, in-depth walk-through of how to read contemplatively. For some people such "dressing up" might help with the sense of reverence; for others it actively interferes with it, making it seem arcane and out-of-touch and lending to the suspicion of being artificial or contrived. In reading that site, it may help to remind to yourself, "the Latin jargon is just a nod to the ancient roots of this discipline." Developing the practice is well worth the time.