To ensure a large amount of actors and actresses turn out for a casting call, you need to advertise as broadly as you can. Posting casting calls on state and city film office websites, Craigslist, job sites such as Monster.com and through arts organizations is the best way to reach your demographic. You can directly inform talent agents in the region of the casting call by calling them as well.
Although the depth of information provided can vary, all casting calls need to include the following information--dates, times and locations of the casting call, shooting dates, a basic storyline synopsis, a description of roles being cast and contact information.
Casting call notices may also include other information. The casting call may invite only SAG members to audition, versus non-union actors. The call may also ask actors to bring a resume and headshot, in addition to stating the callback schedule and daily work rates.