AGE 48 HOMETOWN Elkins Park, Pa. HER BREAKOUT MOMENT The former TV exec-turned-screenwriter gave Showtime its biggest hit since Queer as Folk with her lesbian drama The L Word, an addictive mix of eclectic characters, glam fashion, and soapy story lines. LESSONS LEARNED FROM TOILING IN OBSCURITY Take careful notes. ''You'll know how people think and what corners to duck around. Information and strategy are just as useful as talent and ambition.'' USELESS TRIVIA Chaiken, who has two daughters with architect Miggi Hood, can kick your butt in karate. ''I started going to the studio at age 13 because, believe it or not, I thought the boys were cute!'' NOT SO BEHIND-THE-SCENES ''I was sitting in Le Pain Quotidien with my daughter and somebody came up to me and said, 'If you're who I think you are, then I love your show!''' WHAT'S NEXT L Word's second season on Feb. 20; writing a screenplay for an untitled Paramount drama about a man who assumes the identity of a friend who dies in Iraq.