In the 1988–89 season, she won her first senior national title, ahead of Charlene Wong, and went on to compete at the 1989 World Championships in Paris, where she finished 11th.
Preston began the 1991–92 season with a bronze medal at the 1991 Skate Canada International and went on to win her second national title, outscoring Josée Chouinard for gold.
The following season, she was awarded silver at the 1992 Grand Prix International de Paris, behind Surya Bonaly of France.
In the 1993–94 season, Preston won bronze medals at the 1993 Skate Canada International and Canadian Championships.
During her competitive career, her coaches included Ellen Burka, Osborne Colson, Wally Diestelmeyer, and Louis Stong.