Wendy Crewson and Dillon Casey 'The Vow' Premiere

At the premiere of The Vow, Dillon Casey tells THR his best tactics for picking up on girls.

"I like to add her onto Facebook...just kinda creep her," Casey jokes, "Maybe post things on her wall..."

Wendy Crewson, who plays the doctor for Rachel McAdams' character in the film, met with a real doctor to research her role, but "playing a movie doctor and actually being a real doctor have very little in common" Crewson says.