Thoroughly prepare all of the materials necessary to make a pitch to your potential director. Make sure the screenplay is complete and polished, and give it an additional revision to make sure that your vision and storyline is clear and focused. Write a one-page synopsis of the film that gives a busy director the main ideas of your film project at a glance. Come up with a fleshed-out budget proposal that gives your director an idea of the resources you'll be working with, and include any investors who may already be committed. Include an artistic resume that details your past experience as a writer or filmmaker. Attach a brief cover letter to your entire packet and include all possible contact information.
Frequent the areas that attract potential directors and filmmakers. Independent film festivals are a great place to network with film-industry professionals, and these festivals are held throughout the world. If you can't find a local film festival, try hanging around a local art-house cinema that plays independent and foreign films, which usually attracts people who are interested in the art of film-making. Community colleges and local universities often offer classes on cinematography, film-making and film appreciation and are chock-full of aspiring filmmakers. Enroll in one of these courses, or email the professor and ask them to let their students know about a potential film-making venture that is in search of a director.
Be flexible when you are meeting with potential directors. While you shouldn't completely sacrifice your artistic vision at the whims of a director, film-making is a collaborative process. The director may see an element in the script that you had not noticed, or propose some technical changes that may serve the ultimate goal of the story. Even if you think the screenplay is in its final form or that the concept is bullet-proof, allow yourself to go back with the director and look at it through new eyes. There is nothing less conducive to a successful artistic partnership than someone who is unwilling to collaborate and is determined to do things their own way.