Get your face in front of the director and producers of the film you want to work on by requesting that your regular local agent submit your personal reel to a primary agent in the main production city. It is not uncommon for agents to share a client if that client is willing to travel for auditions and work. An applicable reel should show a range of emotions that would be required of you in the film in question. This means, if you want to audition for a comedy, do not send a compilation of clips from short dramatic independent films you've done. You're better off submitting a comedic monologue.
Securing an agent in the area offering the production work is the surest way to get called in for an audition once the casting team hits town. If you live in Louisiana and recently found out that a movie preparing to shoot in Shreveport has a character that suits you, call and request an appointment with a Shreveport agency. Maintain an open line of communication with this agency and build a relationship for future project consideration as well. Convince this new agent that you will do whatever it takes to get into town for auditions when she calls, regardless of personal sacrifice.
If you don't have a local agent, and an agent in the primary production city won't agree to submit you, find the casting director associated with the film and self-submit. This option requires ample research ahead of shooting time. Pay attention to preproduction dates because this it the time you want to be considered. Don't wait until the movie is slated as being "in production" and all film roles have already been cast. Modern technology makes submitting for work out of your local area easy. Upload your photo to applicable websites, and enjoy casting directors viewing your headshots there and contacting you directly. Submit only to roles you are perfect for according to character breakdown, and avoid appearing amateurish.
Films often shoot in various locations, and when traveling outside the local studio's area, conduct nationwide casting sessions to secure talent. Verify whether or not the movie you wish to audition for plans on conducting a casting call in your city. Often, when a project ends up doing this, it is at the last minute. Requests to see local talent in the selected cities areas are made through local talent agencies. If you're searching industry audition ads in the backs of trade magazines or alternate industry resource papers, call and secure an audition with the agency put in charge for those local issues.