Build an acting portfolio that includes a short bio and a list of all your acting credits. Include any talent contests you've won, any modeling jobs, singing or dancing jobs, and anything else you've done professionally that applies to the entertainment field. The more talent you can demonstrate, the better your odds of getting a top-notch agency to represent you. Include five or six 8X10 glossy shots, in color and in black and white. Make a DVD audition performance to include with your portfolio. It can be something from a past acting job or simply a cold reading of a script, as long as it showcases your acting ability.
Find and agency you think will be a good match for you. Top agencies for actors include the Creative Artists Agency (CAA), International Creative Management (ICM), United Talent Agency (UTA), and the William Morris Endeavor Entertainment group. HollywoodAuditions.com is a comprehensive acting website that offers an online search for agents and auditions by state as well as additional valuable information regarding agents and actors.
Submit your acting resume and three or four 8X10 headshots to the agency you think you may want to sign with. Follow the agencies guidelines for submitting your portfolio. Be sure to include any acting, singing, or modeling credits in your resume, along with a short bio and your headshots. Include a short letter as well, thanking the agency for taking the time to consider you. If you have a recorded performance, include the performance on DVD with your submission, unless an agency specifically states to submit only your portfolio.
Be persistent. If one agency passes on representing you, approach another agency. If you get constructive advice along with a rejection, heed the advice and work on what you can to improve yourself. Getting agency representation may take some time, but if you have the determination it takes, you can find success.