Taylor Swift Makes Her Toronto Film Fest Debut

Taylor Swift made her debut at the star-studded Toronto International Film Festival Monday to promote One Chance, for which she wrote a song for British actress Alexandra Roach's character Julie-Ann Cooper to perform at the end of the film.

One Chance tells the true story of opera star Paul Potts' rise to fame from working at a cell phone store to winning Britain's Got Talent in 2007.

Pics: Taylor Swift's Most Adorable Styles

"The inspiration from the song came from the characters in the movie," Swift told ET at the film's premiere. " ... The support that Paul Potts gets from everyone around him -- especially his girlfriend -- was so inspiring to me cause, I don't know, if you can love someone when you've seen them at their absolute worst, I think that's a story really worth telling you know?"

As for looking spectacular in a high-neck cut-out Calvin Klein dress on the red carpet, the statuesque 23-year-old has one beauty tip she can share.

"Either do a heavy eye or a red lip -- never both," she dished. "Either do an eye or a lip, but just don't do both, or else it'll just ... you'll just scare people."

Video: Taylor Swift Dishes on Regrets

One Chance is being released in the UK on October 25.