Little is known about Valentine's early life. In 1979, she had her sole acting role in Charlie's Angels, starring in an uncredited role as a cheerleader. In 1988, Valentine found work as a script supervisor and has since supervised the episode scripts for a number of TV shows, including Fired Up, Jenny, Beverly Hills, 90210, Charmed, Gilmore Girls, It's Always Sunny in Philadelphia, Nip/Tuck, and NCIS: Los Angeles. More recently, she began work in the fields of directing, producing, and writing.