Use the wrong kind of pen, and you risk having an autograph that disappears into oblivion. “Sharpies are only good for photos and programs,” says Jared Weiss, the president of Steiner Sports Marketing, a company that works with Derek Jeter and Johnny Damon, among others. “On baseballs, they bleed and fade.” So bring a ballpoint pen. Weiss recommends using blue ink in order to visually differentiate your legit autograph from the machine-stamped signatures—which usually come in black—on mass-produced memorabilia.