Tatiana Maslany said in an interview that she has a continuity team that keeps her from mixing up the characters. For instance, if she's doing a scene that has both Alison and Sarah in it and she's playing Alison, if the script tells her to roll her eyes, they make sure it's an 'Alison' eye roll and not a 'Sarah' eye roll.
Tatiana Maslany and writer Graeme Manson would collaborate and agree on a backstory for each of the clones, including their parentage and upbringing.
To help her prepare to play her "clones," Tatiana Maslany created playlists and dances which she thought epitomised their character. She gave Cosima 'rave dance' (with glow sticks), Alison ballet, and Helena was kept private in her trailer.
Scenes with two clones interacting were shot twice with Kathryn Alexandre standing in for Tatiana Maslany as each of the clones in turn, and then blended by digital magic, hiding Kathryn Alexandre's face and voice. Director John Fawcett described it as a "very time consuming process."
Tatiana Maslany is the only Canadian woman to win the Emmy award in the "Best Actress - Drama" category.