You just have to learn to 'tune in' to their channel - listen with your thoughts and look a the images that apeear on the screen behind your eyes. Older crystals will have more messages as they have experienced more frequencies in their time on the Earth plane and stored more information. Many crystals are record keepers, especially those from ancient civilizations, such as Atlantis. Crystal skulls, made from very old crystals, are example of ancient crystals. They seem to have an endless amount of messages to give.
Most crystals have flat areas through which one can look.
These areas are called windows or doors. More experienced readers, such as myself, can pick up any crystal almost instinctively and feel the energies as if it is talking to me. They can heal you while you are working with them though you don't realize it as first. They simple balance the energies in your physical and other bodies. You can place your crystal over a light of some kind to get a better look at the inside.