TORONTO -- Intimacy co-ordinator Ita O'Brien, who is known for her work in series featuring powerful sexual content such as "I May Destroy You," "Sex Education" and "Normal People," says the key to a believable sex scene is preparation and ensuring the actors involved feel safe on set.

"The day on set is the tip of the iceberg, and actually what makes the day on set go well is all that preparation," O'Brien said during a virtual talk over the weekend during the Toronto International Film Festival's Bell Digital Talks program.

O'Brien said intimate scenes have the potential to create a deeper understanding of the film's characters and "enrich storytelling" when they involve more than just the physicality of the moment.

"Of course it's going to be pretend, that's what we're in the business of, and so there's techniques in order to teach you so that it's done safely, but believable and exciting," O'Brien told moderator, actor and director Madeleine Sims-Fewer.

Since 2014, O'Brien has been developing best practices when working with intimate moments, scenes with sexual content, and nudity in film, TV, and theatre. These are known as the '. They are widely used by leading film production houses including HBO and Netflix.

"The intimacy guidelines give us structure by which we can all work openly and professionally with the intimate content, allowing you to bring all of our skills as the actor to the intimate scenes," she said.

O'Brien, who pioneered the role of an intimacy co-ordinator, says the job is different from that of a coach. While an acting coach would work with an actor one-on-one, O'Brien said an intimacy co-ordinator works with the entire production of a scene to ensure everyone -- from the crew to the actors and director -- is on the same page.

"We're literally doing exactly the same for intimate content as a stunt co-ordinator," O'Brien explained.

O'Brien says there are three overriding tenants to her intimacy guidelines. The first being, "open communication and transparency."

O'Brien said it is important for the cast and crew to prepare weeks ahead of time and talk about what everyone needs ahead of a sex scene, such as modest clothing from the wardrobe department or a warming tent from set production if the scene is outside.

She said directors need to check in with the actors to express their vision and to also ask what their nudity requirements are and if they have any sexual boundaries.

"You have that open communication and then agreement and consent," she said.

O'Brien said communication is especially important when it comes to portraying scenes of sexual violence or abuse to ensure the actors still feel safe while exploring a situation of "consent being taken away from somebody."

When it comes to the actual details of the physical movement, O'Brien says "clear choreography" is necessary. She added that the scene should be choreographed like that of a fight or dance. Then, the moves should be rehearsed multiple times before the camera rolls to ensure everyone feels comfortable with what is being portrayed, she said.

"What you're looking for is allowing the actor to be full of what the storytelling is, how this moment pushes the storytelling forward, what it tells you about each character, and each character's relationship," O'Brien said.

Whether in rehearsals or during filming, O'Brien said intimacy co-ordinators also implement timeouts, which give actors the autonomy to stop the scene should they begin to feel uncomfortable, similar to that of a director calling "cut."

Lastly, O'Brien says the intimate scene should operate as a "closed set," meaning the filming only includes those cast and crew members who are directly involved. As well, she said all other monitors outside of the set should be turned off during the scene to prevent a "gratuitous gaze."

For those select crew members involved in the scene, O'Brien said the director should consider early on if they can bring more gender parity to the set.

For example, if it is a heterosexual sex scene, O'Brien said there may just be one female actor working with a male actor, surrounded by a crew of men.

O'Brien said just swapping out a few male crew members with women can help to create a more comfortable work environment for female actors.

However, being an intimacy co-ordinator isn't just about keeping people safe.

O'Brien said her job is integral in creating intimate scenes "of value" for a film that help audiences understand themselves better in their sexual expression.

By creating a "clear, professional structure" for intimate scenes, O'Brien said film productions are able to normalize sexual content in film without making the actors, or audiences, feel vulnerable.