If you want to become a stand-in, you have to realize that it's not an acting opportunity. Stand-ins have the job of replacing an actor's physical form for the sake of photographic appearance only. In some cases, a stand-in may run lines with lead actors in a production, but this work is off camera. If you look like a popular lead actor or actress, you have the best chance to become a stand-in body double for that person.
Body doubles, once they are dressed in clothing, hair and makeup similar to the star's, may look so much like an actor or actress that they are often used on camera in some scenes. Body doubles for television stars may get long-term, full-time work. If you want to become a stand-in who is a body double, you'll have to approach the casting agents for that particular show and convince them of how much you look like their star actor or actress. It will likely take polite persistence, as well as body double looks, before you will be able to register with that casting agency.
A body double doesn't have a speaking role, but rather films some scenes in place of the actor, such as running in a park or taking a shower. Stunt doubles are professionals trained in performing action stunts, such as driving a speeding car or running out of a burning building. Most action movies employ stunt doubles, while many feature films and television series use a body double.
A calm, patient attitude plus the ability to take direction well are qualities you must have if you want to become a stand-in for the film or television industries. Keep ahead of what films or television shows are scheduled to be shot in your area and approach the casting agencies working with these productions. Your goal is to get these agencies to register you. If you have a professional, mature outlook and are prepared with a head shot, casting agents may consider you to become a stand-in for their production. A head shot is a professionally taken photograph of the face from the neck or shoulders up.
Another crucial quality for an aspiring stand-in to have is to be prepared to work on short notice. To become a stand-in, you'll have to be ready to cover for an actor or actress who gets sick or injured or doesn't show up for filming; the entire production can't simply come to a stand-still waiting for one person. Instead, a stand-in is used to substitute for the performer. The crew will then be able to position the props and set up for camera shots. If a lead actor is missing from a rehearsal, a stand-in may be asked to deliver or "feed" lines to the other actors to help them get the flow of each scene, but it's not considered an acting job.