I think the big difference between New Age (pagan/God-less) mysticism and Christian is that the former is about controlling others and things and demands sensual stimuli (is basically prideful), whereas Christian mysticism is about the dark walk of faith, in which one trusts God with the outcome (is humbling).
Just trust God and He will lead you on your mystical path, but don’t expect the excitement and exaltation that the God-less path promises. When we enter the truth of God, we become less in our own eyes because we see ourselves as we really are. The New Age path is more about seeing ourselves as God.