So you want to be an actor? You have the look, the talent, and the motivation - what else could you possibly need? A talent agent!
A talent agent's job is to get actors work. In most cases, the only way an actor can get work is to have an agent. Agents are really the only people that are able to see what casting calls are available in the entertainment industry. Submissions for union roles are only accepted from agents, never from actors. Agents submit actors for roles that they think they are right for (i.e., age, race, gender, look, talent, etc.), by sending a headshot and resume. If the casting director thinks that actor has the right look and thinks their experience would enable them to be successful in the role, they will call them in for an audition.
Sometimes hundreds of people will audition for the same part. If the actor is selected for the part, their agent will negotiate the contract and appropriate pay. When an actor works, the agent makes money, usually 10 to 20% of what the actor is paid. This is why agents usually have strict criteria about the types of actors they sign on.
There are different types of agents for each type of acting-Commercial, theatrical (for TV and Film), voice-over (for radio), and theater. The larger the agency, the more specialized agents they have. Oftentimes, actors will have a separate agent for each of these specialized types of acting. It is important that you research the type of agency you sign with. Not every agency is right for you. Your goal is to find an agency that is going to work the hardest for you, and has the most vested interest in your career.
In order to get an agent, an actor will need to submit their headshot, resume, and demo reel (if they have one), to the agency. If the agency thinks that you would be an asset to their company, then they will call you in for an audition. When you audition for an agent, you will usually be required to recite a prepared monologue, read lines from a script, and discuss your acting goals with the agents.
Don't be discouraged if you don't get signed from the first agency you audition with. Sometimes, even if they really liked you, they can't sign you if they have too many actors of the same character type. You will need to remain patient and continue auditioning to find the right agency for you.
After you get an agent, your work has only just begun. An actor needs an agent to get auditions, but the actor is the only one who can book the job. If you do poorly at auditions, your agent is going to be less likely to submit you for roles. Not to mention, casting directors will be less likely to call actors in for auditions from that particular agency. Remember that your agent benefits from you booking a job. They want you to succeed! It is imperative that you are well prepared for every audition, remembering that it could be your chance to become an acting star!