n the premier episode of Disney's Lizzie McGuire, Hilary Duff's character longs for her first real bra. Since those angsty younger days, fans have watched both Lizzie and Hilary navigate the turbulent waters of cliques, dating and general teendom.   Of growing up on-camera, Duff has said, "I was going through what Lizzie was going through�that teenager stage where you don't really know who you are."   Recent career moves suggest she's got a much better handle on that identity thing now, and that's reflected in her on-screen characters too. In Raise Your Voice, Duff stars as Terri Fletcher, a small-town-girl with a great big voice, and an even bigger pile of roadblocks on the way to her dreams. When Terri gets the chance to spend her summer in a study program at a prestigious Los Angeles music school, it's a move that busts her out of her familiar, small-town world. "This place is the scariest, hardest, best thing that has ever happened to me," says Terri.   Making the break from Lizzie McGuire won't take Duff off any fan's radar screen. With a starring turn in The Perfect Man, due in theatres next year, and a prominent spot on radio with the single "Fly" from her new CD Hilary Duff, this teen's raising her voice loud enough for everyone to hear.