Psychometry is the art of reading an object and the energy left within. Every object we touch or are around picks up traces of energy from us. These traces can give us a subtle feeling, to vivid images of what was happening or what will come to happen.
Learning to read an object is fairly simple if you are practiced at identifying energy. For starters I recommend getting a friend or group to help you practice. Hematite is a wonderful stone to use for this, but you can use any crystal or even a piece of jewelry to start. Each person take an object and hold it for a few moments. Visualize a scene, scent, think of something strongly, whatever it is you wish to portray to the other person. Make sure to really push it but keep it fairly simple at first. When you feel you have done a thorough job switch items. Allow your mind and body to relax feel the object in your hand, its temperature and texture. Let your mind drift on this noting anything you sense the moment it pops up. Discuss this information with each other. It may not work the first try but with practice you should be able to pick up on energy left behind even if the person is not doing it on purpose.
For a slightly more advanced practice get a group of friends and an object that has been recently cleansed. Sit in a circle and pass the object from one person to another. Each person should hold it taking the time to focus on the energy in it, and adding a bit of their own. My favorite way of doing this is to have someone start off a story and each person adds a plot twist to it. I suggest writing down what you felt and what you added before passing it over. Share notes and see what people come up with.
This is a valuable tool when working in the occult and just life in general. Not getting answers from your cards? Check to see if they feel clogged up from previous readings. All of a sudden feeling negative (or any other emotion) after getting a gift and your life circumstances do not seem to be the cause? Read the item it could very well need cleansing. People can pour an awful lot of energy into an item, knowingly or not.