Want to start collecting lithographs? Take a lithography class. Thinking about buying an antique desk? Bone up on your carpentry skills. "If you're learning two-dimensionally, you're never going to be able to encounter problems that a maker or a forger would have come up against," says Dowling. "If you do it yourself, your eye is going to be so much keener on spotting what you think is the mistake. It's going to be far more difficult to fool you." And you don't need to become a master. Dowling says it only takes about three or four, say, pottery classes to know how a bowl, jar, or mug is made.