I am a practicing Crystal Therapist. I am also a massage therapist as well as a crystal intuitive. A good background in human anatomy and physiology is quite helpful. However a good knowledge for the stones, what they heal and the chakra system is equally important.
I am quite accurate using stone layouts with no knowledge of the issues of the person I am working with, much to the surprise of even the most skeptical.
Practice is a key component and trusting your intuition. Learn about the stones and their properties and learn to listen to the stones. I truly believe anyone can learn to be sensitive to stone energies.